Hey, sorry to hear about the diagnosis. It is not fun, but it can be managed. With an ACHR of 54 was it, you have MG. I can't say you DON'T have ALS or some other illness concurrently. BUT I can say that if it walks like a duck and quacks like a duck.................it's probably a duck. It is not at all unusual to begin with just mestinon and have things progress to the point of needing additional treatments/meds added to the regimen. This is where having a good neuro you trust and who knows MG AND isn't afraid to think outside the box to get the best possible regimen for your case.
Again, it sure is MG. And yes you could have something else as well, but that is rare.
Deb