I have pain behind my left knee. It is a sharp, almost stinging pain. Not associated with the kneecap. It feels better when I go to a reformer pilates class (which I do at least 4 times per week) but lately my knee has gotten worse. It is very painful to squat and somewhat painful to walk. It is worse when I am inactive but it hurts pretty much all the time now. I am in pretty good shape. 61 year old woman, probably could lose a few pounds (I am 5 6 and weigh 150 lbs), I exercise and garden and play golf and I don t want to stop any of these activities. It isn t a hamstring pull (or at least I don t think that it is) but it does feel to me more like a muscle or tendon problem as opposed to a joint or bone problem,