At the same time that you are being evaluated for MG, BE SURE and request a test for Celiac Disease. It's much more common than most people (doctors included!) realize, but it is oftentimes seen in conjunction with other auto-immune diseases (you already have RA).

Celiac Disease is easily treated (eliminating gluten from your diet), and in treating it, you may also be able to lessen some of your other RA symptoms. It may also help with some aspects of MG. The fact that you have one (and possibly 2) AI conditions should be justification enough for your doctor to run the test - it's a simple blood test.

My daughter and I were diagnosed with CD two years ago, so I have been on a GF diet for a while (I was just diagnosed with MG). If you have any questions about CD and/or gluten-free issues, please feel free to contact me.

Here's more information about Celiac Disease:
http://neurotalk.psychcentral.com/post8767-2.html