The Pain I'm Having Is Behind My Right Knee. I

The pain I'm having is behind my right knee. I have already been diagnosed with osteoarthritis- but I don't think that's the reason for the pain. The pain doesn't seem to be in the bone. I exercise a lot - the more I do, the more it seems to be aggravated. I try stretching to make it go away. It might get a little better, but doesn't go away. I think it is causing the numbness I sometimes have in my right foot.