I was diagnosed with ELMS within a few minutes on the emg.. they also did send out the bloodwork to the mayo clinic but the emg was definitive.
muscles start out weak you move them a few more times they get stronger.. LEMS..
My symptoms are almost the same as yours and when it all started (3 years ago) it was the same hard to breathe, knees just giving out, started falling, arms would even get sore just drying myself off after a shower.. They checked me first for lyme, then i also forced them to do a western blot, both came back -.

then I was told it was all in my head and i was working and riding my bike to much causing muscle strain and weakness.. I went through a long road of about 3 doctors and 8 months to finally get to someone that diagnosed me..

I was in the hospital many times in the beginning after when it got real hard to breathe and they did nothing.. Just let you sit there because the o2 level was ok..
You are going through what i did at first everyone yanked my chain as to what was wrong until i got really weak..


If you end up with LEMS get somewhere where they can get you 3,4-Diaminopyridine and a mestinon combo this will greatly help you. without to many side effects, I am also on cellcept now after fighting taking it for over a year.. and it is helping somewhat.

MG and LEMS are similar but not the same. I after 3 years of different treatments still can not walk more then 50 yards at a time and still cant even bend down to pick anything up off of the floor because they took so long to diagnose me and i had gotten so dam weak that it will take years for me to ever walk up a set of steps without a banister.. going down steps? forget it.. if there is no banister i have to go down on my a#%.

Good luck Hope they get you officially diagnosed ASAP..