I'm one that has pain with my MG. Although it is not so much pain as aching. I often try to describe it as the ache a normal person would get after doing 10 more sit-ups than their muscles want to do. It basically is the ache of fatigue.
Most medical literature says MG doesn't produce pain, but they really need to rewrite the books! Hopefully some day someone will, and they'll start educating the neuros to deal with the pain their patients face.
Hugs,