Hi Christine!
First of all, Prednisone OFTEN makes MG WORSE before it makes it better. So, if your daughter's doctors don't know this, they need to do research:
http://www.uwo.ca/cns/resident/pocke...uscular/MG.pdf
This is by Dr. Michael Nicolle -- an eminent Canadian MG specialist. Note Prednisone information on pages 9 and 10.
It seems to me that Myasthenics are OFTEN allergic and chemically sensitive -- so, I wouldn't be at all surprised if your daughter has problems handling meds and/or treatments. They are "throwing" so much AT her right now to make her BETTER -- some of this may actually be CAUSING problems.
Hang in there -- it sounds like the doctors ARE looking and ARE concerned.
You and your daughter will be in my thoughts and prayers.
(((HUGS)))