Does anybody get these from working out? I've never gotten these before, but yesterday when I went for my walk/jog at lunch. Both my hands around my thumb started twitching. It was pretty cold outside, and I forgot my jacket. Figured it was from hands getting cold, when I got inside after a few minutes it did stop. Then last night during my sleep I had one in my back. I did just start working out so do you think it's my muscles getting used to it?