Did you know that coconut milk has a diuretic effect?! Meaning that it can dehydrate you?
I think you should talk to a primary doctor about some basic chemistry testing, etc. and the long-term antacid effects.
Antacids can cause you to have low calcium, anemia, low vitamin B12 from not digesting/absorbing it and low protein.
Drugs are useful but there are other solutions to health issues—like finding a CAUSE for a symptom before throwing a drug at it.
Unfortunately, when you have one autoimmune disease, you have to be aware that you could have more. Don't chalk up all new symptoms to MG or the drugs you're on. I have MG, celiac disease, and other misc. junk.
I'm glad you have good doctors to talk to!
Annie