Everyone once in a while, I will wake up in the middle of the night with a horrible pain in my left calf. It feels like a cramp, but worse. I will be on the floor trying not to scream for about 30-50 seconds waiting for it to end. This only happens every 2 months or so, but when it does happen, my leg stays in pain for at least an hour after it occurs. Does anyone else have this or know what causes it?