This is for the ladies -- my mom taught me years and years ago that if you're overheated, you take a cool (not icy cold), wet washcloth and put it under your breasts on the ribcage -- at the bra band area.. Of course, you have to get to a private place to do this (!) but it really does work and the relief is virtually immediate.
She didn't have MS, but had no tolerance for heat.
I don't know how this would help men because I'm not a man and have no experience... as a man.... !!