You mention myelin sheath, well a naturopath suggested 4 remedies for the Burn issue I have dealt with since hip replacement nerve damage which was 5 yrs of burn/tingle.

I took Sphingolin and Inosine for 3 months and the burn/tingle is gone. I still get "twitching" now and then and think MAYBE the nerves are trying to come back but who knows. 80% of my thigh is still numb but burn is gone.

Read up on these two and see what you think. I bought them from pureformulas

Do you feel better now on the Levo? I read your other post and you mentioned under active thyroid.