@labsmom5 In reading your list of diagnoses, there seems to be a lot there that can affect breathing.

Have you been tested for allergies? This certainly can affect how much phlegm is in your lungs obstructing the air ways. I have asthma, and even though I'm treating allergies with shots, it wasn't doing enough for my cat allergy. By making changes at home with using HEPA air filters, and wearing a HEPA quality surgical mask when I'm near the cats, and cleaning/vacuuming to reduce dander, it made a world of difference in my ability to breathe, and I can coexist with my cats. Until I figured out the connection, I would get accumulating phlegm that progressed to lung infections with my heart rate raised. The masks are 3M #1820 Procedure mask with ear loops (not ties) that have >99% Bacterial filtration efficiency and > 99% @ 0.1 Micron particles. If I can prevent the triggers from getting into my lungs, my lungs don't react by producing the excess phlegm.

The spinal stenosis and retro spondolisthesis might be affecting your breathing too. The phrenic nerve exits the spine from the spinal roots of C3, C4, and C5 and travels down next to the spine before passing near the heart and reaching the diaphragm. if you are having vertebrae slipping and neck muscle spasms, it could be affecting the phrenic nerve through a physical compression somewhere in it's pathway. Have you tried any physical therapy to improve your breathing? I'm not suggesting physical exercise, but manual techniques like myofascial release therapy. I am a spine surgery patient with a fusion at C5/C6, and I also have Thoracic Outlet Syndrome (TOS) and that made my neck and chest tight where nerves and vessels were passing through small areas. TOS is common among patients with spine injuries and it affects the mechanics of breathing which I have experienced. Through physical therapy and MFR, I've been able to improve my breathing and get things moving again as they should be. MFR often can help where conventional treatments fail. If you have had long term inflammation, or injuries, the fascia can become tight and restricted. Lung tissue is mostly fascia with blood vessels in it. You can have fascial restrictions into the chest where the nerves are passing. It might be something to look into.

Has anyone offered treatment for your spinal stenosis and retro spondolisthesis? If you have instability there, it's possible this could be a source of phrenic nerve problems from irritation or compression. Are you getting help for the sleep apnea and using a machine to breathe at night? That might help a lot too. One of my friends uses one, and she told me that because she was in panic breathing mode all night, it was raising her anxiety levels during the day, which then again causes breathing using muscles in the upper chest and neck... the same place where tight muscles can affect breathing.

MFR is also treatment for fibromyalgia. It might be worth discussing with your doctor if physical therapy can help. Not all doctors embrace MFR or understand it, but it works, and I have benefited from it a lot. Right after my spine surgery, I did have breathing problems, and the tightness from the surgical path tightened the fascia very close to where the restrictions exists from the TOS, and my pain was worse until we opened up those spaces with MFR work.

I created a discussion about Myofascial Release. There is a lot of information collected there where you can learn about it. There is a provider finder link on the myofascialrelease.com website.
https://connect.mayoclinic.org/discussion/myofascial-release-therapy-mfr-for-treating-compression-and-pain/
Here are some other links you might find helpful.
https://teachmeanatomy.info/neck/nerves/phrenic/
https://www.painscience.com/articles/respiration-connection.php
https://trainingandrehabilitation.com/how-truly-treat-thoracic-outlet-syndrome/
https://www.mayoclinic.org/diseases-conditions/thoracic-outlet-syndrome/symptoms-causes/syc-20353988