Extreme temperature changes cause sudden bowel movements for me. It's horrible. Hot to cold or cold to hot. Inside to outside. I all of a sudden have to go, my stomach cramps up. What could it be?

I have had the same problem all my life! I hadn't had it during the winter, but now it is getting hot outside, and every time I leave an AC environment and go outside into the hot, I get diarrhea immediately (within minutes). I have never met anyone with this problem, and my doctor had no idea what it is.