I have been experiencing cramps for almost a month when I sleep and it is really painful. I'm not an athlete though. And I'm only 20 yrs old. The cramps has subsided for a while but in a few months I've experienced pain behind my right knee and I can't stand on one foot (right) for more than 5 minutes because it becomes painful and stiff.I would like to ask what my condition is? Maybe its only because of exhaustion or something. I hope you can help me. Thank you.