Blondie, re: those links, scary stuff! I'm at risk for the clots, too, but would rather not think about that!
Ferret, yes, I've had them in both legs at the same time, once even traveling up into that big ole butt muscle. I was at the movies with my son, sitting in the middle of the row, not knowing what on earth I was going to do. Talk about panic!
Blondie's link says a strong cramp can break a bone!
Thanks, everyone.