So sorry that you are having a hard time... Waiting for a diagnoses itself is so frustrating, much less having worsened weakness

I also get a pressure sensation on my chest when I can't breathe.. The first time I noticed I had something wrong with my breathing is when I went to sneeze, and that breath you take before the sneeze didnt' really happen.. soon after that started within 3 days or so things worsened fast.. I was so winded talking, couldn't read to my kids (I had a 1 and 2 year old).. couldn't walk more than a few feet.. Showers made me just about collapse , the heat really really affects me.. makes me like a lump of jello on the floor! Finally I crashed.. I coudlnt' breathe, my pulmonary tests were really bad and I got admitted for IVIG.. which thankfully worked wonders!

As others said - don't risk it, when it comes to breathing.. let your dr know your having that chest pressure sensation.. it was so hard .. they were trying to diagnose me, so would do a test.... wait for weeks for the results, then do another.. all the while I declined.. Good luck, keep us updated! (fyi - I still have no formal diagnosis)!