Flutebell, Sorry you're still in the diagnosis limbo. I did not have 'any' positive tests for mg for the first six months, but neuro was 99% sure that was what I had.

Eventually tested positive for Lems, but not until this past December, after four years did I have a positive single fiber EMG.

Don't give up. Keep seeking. Some doctors will treat without a concrete diagnosis. Glad mine did or I don't know what would have become of me.

Before the single fiber, I went off mestinon for 24 hours and dap for about six and I was a limp mess.