Have not been on the site for a while, but I had something somewhat similar to what you describe. My problem was being unable to breathe lying down, and water pressure blocking breathing if it was over my chest. Was diagnosed with a paralyzed right diaphragm. Wound up with a c-pap machine which allowed me to breathe lying down, so I could sleep in bed and not sitting in a chair.
Turned out it was not. What I had is called Parsonage Turner Syndrome, a nervous system disorder. Look it up and compare symptoms.
It's considered rare, with no known cause or cure, just time, they say 5-10 years. What I have found out since.
They believe it can be triggered by an unusually bad flue or cold, one that can drag on for weeks. The symptoms start maybe 3 or 4 months later so the connection to the cold/flue is not always obvious.
In my case I found that acupuncture and osteopath treatments helped, managed to get rid of it in 3 years.
May not be what you have, but worth reading up to see.
Good luck with it.