"Burning" is not normally an MG thing. It makes me wonder if you have lactic acid building up. Write a note to yourself to ask a doctor to check your lactate and pyruvate. And when was the last time you had a comprehensive metabolic panel (to check kidney and liver function) and a UA?

http://emedicine.medscape.com/article/167027-overview

Don't read that now. You need to rest. If you feel worse, just go into the ER or dial 911. Don't get too worried - stress doesn't help anything. You sound pretty calm to me though.

Annie