I have an unusual undiagnosed issue with exhalation

[ThutmoseChen]

I have a symptom that so far I haven't been able to find an answer. I am actually not a native English speaker but a few years ago when I started learning I felt a strange sensation of unable to speak out words that require longer or deeper exhalation. I thought it was a matter of practice but years later I still have this physical difficulty, and I realized that this comes from under my left rib cage, it's like something is pressuring the rib cage so that it can't contract during normal exhalation, but inhalation is fine. When I described my symptoms to people some suggests that it might be related to somatic attack, but to me this sensation feels very physical and consistent, every breath I take, day or night, I feel this awefully unexplainable feeling that my left rib cage is trapped, something (underneath it?) prevents it from moving. What could possibly cause this sensation?

I don't think it's a problem with my lung and I did chest x-ray and abdominal CT scan and both results came back normal. My gastroenterologist suggested the possibility of gastric mobility issue but the drugs for treating that isn't helping. I can't wrap my head around about what is wrong with my body, I can't find people with similar experience, but what I feel is very strong and it persists, not come and goes. My life quality is drastically lowered by this symptom as I have difficulty with communicating and even reading fast (constantly out of breath, so I read almost one word at a time). Any suggestions on what the next step should be for me?