Home Diseases Guide What could be the reason for sudden pain behind knee?

What could be the reason for sudden pain behind knee?

Yesterday, I was watching TV and was sitting in same position for a long time. When I stood up there was a pain behind my knee I sat back down and thought I might’ve just overextended it, but it doesn’t seem so. I couldn’t make it upstairs without the help of my girlfriend and thought I could sleep it off. I just got up this morning and it is extremely painful. I want to know that what I should do in order to get relief from it. Please help…