Weird. Just had one of those mysterious inner thigh cramps that come from sitting on the couch, only this was sitting in the rocking chair, worse luck. But after several agonizing minutes bent over the bed at a 90 degree angle, the one position that doesn't make things worse, I finally remembered the fix-- pressing the skin between thumb and forefinger HARD. At which the pain simply disappeared and I could walk again.
You'd think someone could give a medical name and reason for these things, as also for the cure.