I did this a couple of months ago. I went to my rheumatologist and she ordered a pulmonary function test and chest X-ray but I never got to have the tests due to the corona virus. It eventually went away so I’m not sure what it was. I have anxiety too so I wonder if it wasn’t something to do with that.

I have that problem too. I can't lie down on my back without not being able to breathe. If I fall asleep on my back I'll wind up waking up gasping for air. If I'm on my side I'm fine. Usually my left side is the best. The docs told me that everything with my heart and lungs is fine...i think it may be something to do with a disorder I've heard about recently called POTS.

I did see a pulmonary doc and they had me do the pulmonary breathing test twice. Most of it was normal but something was off so they thought it was the nerves in my chest wall but they still cant figure it out.

See a Pulimary doctor, I did