I suspect docs are careful to make a diagnosis as it can be devastating--they woulde rather hold off and be absolutely sure when it's a disease like MG with unreliable treatments and no cure. My doc will put MG on diagnosis when sending me for tests but won't say that's what it is as he doesn't have everything ruled out. He's sending me to a pulmunary specialist to be sure my shortness of breath isn't due to a lung issue. And also to a neuro diagnostician for a single fiber EMG.
Hope things look up for you more soon.
Susan