not sure how, but i was out wrestling in the snow and i was crouched down but only on one leg and then i got jumped on and when i got back up the back of my knee hurt and felt really weak. Right now it just feels like a muscle cramp that won't go away in the back of my knee/upper calf. is this probably a strained muscle? I haven't run on it yet, but can i? or better, should i?