If they gave you a femoral nerve block
during surgery, there may have been some damage done to the nerve
itself. Pain in the buttock area also would indicate to me sciatic nerve damage as well. What are you doing for the pain as of now?
If acquiring pain medication is out of the question, i would suggest a more holistic approach: massage therapy, Range of Motion exercises (don't strain), warm or cool compresses (whichever you find more relieving).