Aside from nerve gas poisoning, which obviously I could not have had for the last 16 years, what else does Mestinon work on? What else gets better when you take Mestinon, if it isn't MG?

What acts like MG but isn't?
What other diseases does mestinon provide improvement for, besides MG?

AChR negative. MuSK negative. Thyroid tests normal. Rheumatoid diseases blood tests normal/negative.

MG-like weaknesses, including dramatic eye problems, including breathing difficulties. Mestinon provides improvement that even casual acquaintances have noticed and commented on, it is so dramatic an effect.

So, if it's not MG, then what else could it be? Because without a positive test for something, my doctors are saying it's not MG. And started to suggest I should not be on mestinon, even tho it is obviously working so well for me.