The fact that you tested positive for the antibodies means that you have MG. The fact that you tested negative the second time doesn't mean anything. It's pretty common for people who have MG to test differently at different times.

I hope I can reassure you about the Mestinon. 30 mg. is a small dose. If it's too much or you don't need it, you'll get diarrhea, or you'll have small, painless muscle twitches, or your mouth will water a lot. In other words, there are relatively harmless indications that you're taking too much--it's not a crisis or nothing. So if you take the half-pill and it doesn't really do anything, don't be afraid (if the doctor tells you to, of course) to take a whole pill.

Mestinon has a short half-life. Four hours after taking it, it's pretty much out of your system. So if you take it once a day and it helps, then your doctor should tell you to take it three times a day, or every four hours.

Abby