Tyson,
I'm going to sound like I'm beating a dead horse here, but you will want to ask your doctor to test your skin for Dermatitis Herpetiformis. BE SURE and request that the test be done by a dermatologist who is familiar with the correct way to collect a sample. At the same time, have them run a blood test to screen for Celiac Disease. You may want to contact your local Gluten Intolerance Group (GIG) for recommendations for a doctor in your area who is familiar with CD/DH.

I have DH, which is the dermatological manifestation of CD. About 10% of people with DH will NOT test positive for CD (I happen to be one of them), but if you have DH, you have CD; the antibodies are expressed through the skin rather than through the blood. Since you already have one auto-immune disease (MG), you are more likely to develop another one. Celiac Disease is MUCH more common than most doctors realize (1-in-133 people are estimated to currently have it, yet only 3% of them know that they have it).

DH itches like an SOB! The good news is that if you go on a gluten-free diet, your lesions will start to clear up almost immediately. You may also find that some of your MG symptoms are lessened as well. If you have any questions, please feel free to contact me - I've been on a GF diet for the past 2 years, and it made a HUGE difference in how I felt. I was just recently diagnosed with MG, and my doctor feels that the GF diet might be why my symptoms are so mild....

Unfortunately, the skin test for DH won't always give an accurate result, so you may want to try a completely GF diet (there's no such thing as "gluten lite") for about a month to see if it helps at all. Have the test run anyway, just on the off chance that it comes back positive. However, a GF diet won't HURT you in any way, so it's worth it just to give it a try; you may find that you feel better on it, whether it helps your rash or not.

Gluten-Free foods are the fastest-growing segment of the food industry, as more and more people are becoming aware that they have gluten issues. Many restaurants have dedicated GF menus as well; our local GIG group puts out a Restaurant Guide, which made it SOOOO much easier for our family when we were starting out!

Here's a link to some info on Celiac Disease and gluten issues:
http://neurotalk.psychcentral.com/post8767-2.html

And here's a link to a list of professionals in a few states that have GIG support groups:
http://gluten.net/professionals.php

If your state isn't listed, you may be able to find one through the celiac.com website on the neurotalk link - I believe they have a listing of support groups in the various states.

Hope this helps!