--heat is the enemy of nerve function, though it may be soothing for muscular aches.

The MS people know this well--they are constantly trying to stay at cooler temperatures, and there are even cooling vests sold to keep the core body temperature a little lower on warm days.

I'm interested in the fact that your magnesium supplement has B6 in it--what are the levels? There are some people with metabolic issues involving B6 that get neuropathic symptoms at high B6 supplement levels--they may not be able to properly convert pyrodoxine (Mrs. D may chime in which a much more detailed analysis). It might be a good idea to try the magnesium without the B6 for a while.