Hey DesertFlower, have you had your thyroid checked lately? I think 10% of people who have MG also have Graves disease (hyperthyroidism). I do. When I'm hyper, I stutter and shake--but not all the time; only when something "sets me off." One thing that sets me off is doing too much. Maybe the Mestinon allows you to do too much, and that sets off your thyroid.

Just a wild guess, but worth looking into! People with MG should have their thyroids checked. A thyroid blood test is simple, and unlike MG, Graves is easy to treat!

Abby