Chef,
First, try and get a new neurologist that specializes in Myasthenia Gravis. I assume you live in the U.K., so I’m not sure how the NHS works trying to change doctors, but if your tests came back positive for MG and your neurologist won’t help you it is time to find a new doctor. Second, search this site for ‘AnnieB’. She is a nurse with MG and always posted about breathing issues and the tests you should have. Best of luck. Jim