How Can Severe Pain In The Buttocks After Knee Replacement Be Treated?

at three months from a total knee replacement in my left knee, I began to have severe pain in my left buttock. I was given exercise to increase lower back strength, which I did pretty faithfully. The pain is still there and at times so severe I can t stand up. It is not a skeletal issue, I ve been checked for hip and leg movement and they are good. I suspect that, since I need my right knee replaced, the imbalance has caused the problem. Prednisone is extremely helpful, but the side effects are worrying. My doctor yesterday (injections in my right knee) suspects a hamstring issue, but I m not convinced. I m feeling very frustrated as the pain is still with me for the last three months unless I am on Prednisone.