Wanted to share some info after reading this entire thread. This will be lengthy as I have many thoughts on this issue.
Like a few posters on here, I am medical and have experience seeing this issue but I also have dealt with it myself and currently am dealing with it.
I developed very mild symptoms last summer, knew what it was (because I have had it before), didn't worry about it and no big deal but it worsened when I developed some other symptoms and I because I worry about what symptoms can mean (b/c of my medical knowledge) it spiraled out of control and a few months later I am still dealing with it even though my initial worry about something organic being the problem has resolved through reassuring tests.
The majority of posters on here deal with unexplained shortness of breath/air hunger; medical evaluation, often very thorough, is unrevealing.
The general terms applied to this condition is dysfunctional breathing; hyperventilation is also used.
There are several different ways this can manifest; true hyperventilation syndrome manifests with episodes of very rapid breathing and other symptoms due to blowing off CO2.
A lot of posters have another form characterized by the ongoing need to get more air- the constant perception of air hunger which results in exaggerated inspirations/sighs. For most on here, it is chronic rather than episodic.
There is some insight to what may cause this, with the thought that there is some derangement in the respiratory drive, and things can affect this like emotion. Some believe that in overbreathing, patients maintain a low CO2 and then enter a state where they become very sensitive to rises in CO2, which is what drives the excess breathing.
One easy way to check your tolerance to CO2 by inhaling, exhaling, then holding your breath after exhale. If your time is less than 20 secs, that is typical.
The "root" cause that everyone would like to know is unclear but without question, there is a psychological component to this.
Generally when I have experienced it there is an underlying stressor, whether recognized or not. And certainly if there is stress related to the condition that will not help.
Many posters mention GERD/LPR ("silent reflux"). I have it. Is it related? It is unclear. I know there is a blog that mentions esophagitis as a cause of "pseudodyspnea". You won't find that in the traditional medical literature. Those conditions are common anyway and most don't have this breathing thing. Acid reflux can worsen with stress, so is it reflective of the underlying stress? I don't know, but I don't believe this is simply a function of acid reflux.
Many on here feel they are being dismissed if this is attributed to anxiety but I think that is because they perceive that they are being told the symptoms aren't "real."
Whether a symptom is organic in origin, or psychogenic, it is "real." Your mental health plays a huge role in your physical health/symptoms.
What is clear is there is no simple fix. A few things are clear: when a multitude of tests are normal, accepting that this disorder is not a function of something organic is helpful. The typical causes of dyspnea are readily diagnosable including pulmonary and cardiovascular causes. While negative results are normally reassuring, most probably are left questioning "why do I feel so bad?" and most doctors don't do well explaining symptoms like this in the face of negative tests.
It is difficult, but the focus can't be on the symptom- it will just perpetuate it. Many mention distraction helps and this isn't coincidental.
A nurse posted recently and that has become her philosophy- accept it and move on and over time it will be less intrusive in your life and will eventually fade.
I encourage everyone to, as best they can, lead their life as normally as they can and don't make accommodations for this. If you let it in, it can overtake your life.
Posters have mentioned a pulse oximeter- they are cheap. I encourage obtaining one and no matter how short of breath or hungry for air you feel, if you check your oxygen level it should be normal- 95% or higher- that can be reassuring. That means your heart and lungs are working effectively to oxygenate your blood which is the most important aspect. People with heart disease or pulmonary disease who get short of breath will often not maintain their oxygen level.
Various things work for various people. Some people get better with GERD treatment; some improve with antidepressants/anxiety treatment. Some mention supplements/diet. At this point, there is not one simple fix.
Regardless of whether it is a placebo response or "real" response, it doesn't matter. Placebo responses are real, and in a condition like this, I suspect that believing that the treatment will work is probably as important as anything.
This condition reflects that there is a mind/body connection. I have had instances of literally worrying myself sick when I would get such severe symptoms that I "knew" I absolutely had to have something wrong with me. Over time, with reassurance, these episodes would fade and I would get back to normal. Unfortunately, I am prone to worry/anxiety related to health and if something is going on psychologically, this can manifest with "real" symptoms but there is no organic cause. This can cause worry and the cycle can begin.
It is unfortunate but reality that as common as this condition is, little is known about it. I'm in a position to know and I have no idea who I could see that would deal with this condition. The various specialists are good at ruling out diseases and that plays a role in this condition; when there is no evidence of disease, they don't always have good explanations.
I appreciate all who have shared their stories. There is some comfort knowing how common this is. I gleaned some information reading through the stories.
My advice is accept that despite how bad your symptoms might be, if you have had those reassuring tests, tell yourself you are healthy. You may not feel healthy, but you are. Live your life, exercise, etc. If you have depression/anxiety, get it treated; same for reflux. If you want to follow a diet, do it. If you believe you will get better, you will. You will hopefully find stretches where you forget about the symptoms and those become more and more frequent and eventually the problem fades.