I, too, have a host of GI problems. Have you been tested for SIBO? It is a simple breath test that will show if you are excreting methane, hydrogen or both. Methane is commonly associated w constipation vs hydrogen which tends to have more of a diarrhetic effect (thou I'm positive for both methane and hydrogen but my chief complaint is ZERO motility).

There is so much to be learned about the brain bowel connection and with all the work being done on the microbiome I wouldn't be at all surprised if diseases like MG could be cured or at least mitigated by reconstituting gut flora.

Btw, I also have celiac and showed positive antibodies for pernicious anemia so, again, I firmly believe they are connected.

Good luck!