Hi, Lily! I can really relate to your experiences. Not with my initial diagnosis of Myasthenia Gravis, which was given me in the mid 70's by an MG specialist. But since then I've been to 3 other neurologists. One agreed with the diagnosis and gave me steroids, a normal treatment for myasthenics, but which can go very wrong in the case of a few. Guess who was one of the few! Once out of the hospital, I went back to the clinic and was seen by a different neuro, who did a test for antibodies. 30% of myasthenics are negative for these. Guess which group I fell into! Of course, he said that since I was sero-negative, I could not possibly have MG. And would you believe, he had no record of my having been taken out of there by ambulance in a myasthenic crisis the last time I was there! Since then I've been to one other neurologist, who had a particular muscle test done, which also was negative. No matter that he failed to tell me to be off my medication for several days, as the medication could mask the condition. Or that the test was done with a malfunctioning machine, by a technician who was being trained. Nope, it's negative so I don't have MG.
Fortunately in my case, I have the support of a very caring GP, who has seen me at my worst, and knows it is MG and that MG is never the same in different patients. Through her I have access to my medication, though there are several others that I could be taking if a neuro prescribed them.
I hope you get the answers you need. Being in diagnostic limbo is not a pleasant place to be!
Hugs,