Hi @gabrielm I have never posted on one of these forums before but your original post describing the inability to get a good deep breath or a satisfying yawn intrigued me and I thought I would share my experience.

I am 41F and had these health conditions long before this started for me:
Life-long chronic asthma (usually triggered by illness)
Non- allergic rhinitis (so many symptoms always negative allergy tests)
Migraines
Prone to viruses and infections since childhood

Then came the mysterious SOB, chest tightness and unsatisfying yawns from out of no where. Makes me miserable. Like difficulty focusing on anything else and exhausted from not even sleeping well because of it.

Pulmonologist/immunologist prescribed Prednisone which, I think, helped some but the miserable inability to breathe deeply came right back when the meds were gone. Back to the same Dr and she trys adding a new inhaler to my daily regimen. I want that to help so much but nope, I still can't get no satisfaction. Back to the same Dr who starts sending me for every test imaginable. Lungs, heart, ENT, allergies, CT scans, lung function, stress test, a gazillion labs. Honestly nothing is showing up, my asthma is not that severe and seems pretty well under control. The only exception are the labs for my immune system were not great. She confirmed that I had been properly vaccinated as a child and then said the tests showed some kind of immuno-dysfunction. So she sent me to get a test vaccine to see what would happen. First labs after that were fine, I still had immunity. My doctor all throughout this has been thorough and kind, she says we have to wait to see over time to see if I retain my new immunity.

The pulmonologist believes me regarding the breathing problem, which is something at least. She has me start steroid nasal rinses. If you haven't done those every morning, you are really missing out, let me tell you. The pulmonologist wonders could it be vocal chord dysfunction and sends me to a voice therapist while we wait to retest. The voice therapist is great and compares notes with the ENT but rules out VCD. She however suggests Prilosec in case it's GERD. Sure why not? I'm just a test subject now anyway.

Meanwhile, I am still miserable and feeling like I can't breathe well, even though the results of the all the tests so far show I'm supposedly fine. It's slightly comforting to know you aren't dying when it feels like you are. Discouraged and desperate. I started searching online for clues. I try breathing exercises, calming exercises. Changing diet. Making sure I am not stressed. Drinking more water. And searching the most remote forums of the medical internet. I find a lot of people complain of similar symptoms but no one has an answer. Such a mystery. And then one day, I stumbled on to something. The article talked about Mast Cell Activation Syndrome. I was like, oh great another one of those internet conditions that people use as an excuse for why they can't eat gluten or dairy or any other foods that people all over the globe have consistently eaten for millennia. Nope I definitely don't want to have that. But the symptoms list included a bunch of stuff that I had always struggled with AND the feeling like you couldn't get a satisfying breath. Consider me curious. Not enough to buy the books sold by internet doctors but definitely wondering if there was anything that others had found worked to help the breathing thing. Remarkably the treatment seemed consistent across multiple sites and it wasn't some kind of expensive supplement or exclusive diet. It was a regimen of antihistamines. What??? No way that would do anything. But gosh...it can't hurt to ask the Dr., right?

So when I went back for blood work the Dr asked how I was doing? I said I was still feeling that struggle to breathe deeply and I couldn't remember the last time I had a satisfying yawn. And she stopped what she was doing and said, "the mind and the body are very connected. What has been going on at home lately? Have you thought about seeing a therapist?" I was immediately so frustrated and felt tears welling up in my eyes. Not the best way to prove I was emotionally and mentally sound. Lol However I got myself together and firmly said, "Look everything at home is fine. Except me, because I feel like I can't breathe. And not being able to yawn, as freaking crazy as that sounds, is what is making me miserable and it's not the other way around at all. But I assured her I was willing to try ANYTHING and would call a therapist. However, I finally mustered up the nerve to tell her I also had an idea I wanted to run by her. So I told her about my internet research. And learning about MCAS. That is all the doctor's very favorite thing, when their patients google the things they spent years and years and years of their lives studying. I'm sure she was just patiently humoring me and didn't think it was going to work. But she agreed that the extra doses of antihistamines wouldn't be dangerous even if they didn't help.

So I went home and got my meds together. I decided to do Claritin, Zyrtec and Zantac (instead of Prilosec) twice a day and just see what would happen. Yeah that was before we knew about Zantac's evil cancer causing properties. I ended up switching that out for Pepcid. Honestly I don't think I had my hopes all that high that it was going to help and for the first couple days I don't think it did. But a few days in and started noticing a sneaky good yawn. Not every time, but just here and there, every so often I would feel that satisfaction of a really good deep breath. At first I thought it was a fluke. But by the second week, it was happening more and more often. Ahhhh. Relief. I could breathe fully again.

Going back to the pulmonologist, I was like there's no way she is going to believe me. But she did! She didn't have great news for me about my immunity. And she wanted to start me on treatment for that. But when I described how much the antihistamines were helping me, she was really glad for me. I said I didn't think it even made any sense why they would have worked and she said oh it actually does make sense to me and then some Dr mumbo jumbo or other. I was ready to ditch the new inhaler right then and there and she could see I obviously felt much better and she told me she was really glad but we'd continue all that we were doing for the time being and hope it kept working.
So... over a year later... I'm happy to say it's still working. I have had some brief times where my breathing has been a little sketchy but I think it is connected to allergic type triggers. And overall I am doing so much better!!!! I am still using the asthma meds and have also added quercetin twice daily and Nasal Crom spray as needed.

Obviously I'm not a doctor. But OMG it's working for me. Nothing in this post is speculating that anyone else has the same diagnosis as I do or that what my doctor and I have tried for me will help you. What I hope to convey with this post, is that your health is worth fighting for. If at first you don't succeed, keep trying until you get the answers you need. And if your doctor is unwilling to help you adequately, then find a new doctor. You are paying them and nobody has time for that crap.

I would be glad to answer any questions y'all might have for me.