Tracey, Did your doctor even test you for the TPMT test BEFORE putting you on Imuran?!! If you're lacking in this enzyme, you could still have Imuran in your body. Have they done extensive liver studies to make sure your liver is functioning well now?
When the liver gets toxic, it can have trouble detoxifying you of other drugs, such as Cellcept. It's possible that your body can't handle big drugs right now. I have no way of knowing, only your doctors can figure that out!
The body clears toxins via the liver and kidneys (it varies according to what drug you are taking).
Your endocriologist could do a comprehensive chem panel, urinalysis, etc. to determine your overall metabolic health, plus how your thyroid is doing, like Abby said.
Also, liver toxicity can also cause problems with cholesterol. It can create a Vitamin B12 deficiency (B12 is stored in the liver). And so many other problems that could contribute to your overall "lack" of good health.
Please don't give up hope! I just think you need a doctor or two to help you figure out what your current health is and what is contributing to you being worse. It's quite possible that it's more than MG and your thyroid causing you to feel worse. Please, you need your liver! Unless someone figures out exactly what is going on, how can you really know if your liver can handle drugs?
I hope I didn't stress you out. Do you have someone who can go with you to a doctor to help you with all of this? Sometimes it really helps to have someone be your advocate so that you don't get more worn out just trying to get help. Please let us know how you're doing, okay?
I have to add that some thyroid patients do better on thyroid drugs like Armour Thyroid and Nature-Throid. What drug are you on?