Elf Sternberg

I'd go with the potassium/calcium angle, followed by enough water. I always get muscle cramps when I don't eat enough potassium with calcium to balance it out, and being dehydrated is just asking for it. Your cramp sounded particularly bad, but about right for the ones I've had. I usually limp the rest of the day until I can manage to sloooowly stretch it out again - while eating two bananas, drinking milk, and about two quarts of water.

Dried apricots are a good banana alternative - have a good amount, and you can keep them around for more than a week. I use those when my bananas are gone, since they can't last more than a week in the house.