buttock pain immediately post knee replacement

I had a knee (R) replacement just over a month ago. When I woke in recovery, my R buttock was more painfull then my knee. It did not moderate. I discussed it with my physical therapist (a stretch was recommended, which I have been doing 2-3x a day)and at my 2 week post surgery appointment. They gave me some muscle relaxants to take at night, and they really helped reduce the pain. Now that it's not constant, I realize it's worse anytime I bend that knee with weight on it, such as walking. Any ideas on how to mitigate this pain?