OK, all of my medical experts on here, tell me what this is: Last night I was sitting with my leg curled under me and I got a terrible pain in my knee and it was locked up; had a terrible time straightening it out. When I finally got it straight, there was a big pop. The problem was not in the knee itself, but in the back, kind of to the outside. Today it is stiff and sore. I had this happen a couple of times several years ago but have been doing OK till now. Anybody know what this is? Should I put heat on it? Cold? Cut off my leg? What do you think?