In Mid-October I Started Having Pain In My Left Butt

In mid-October I started having pain in my left butt which I thought was a pinched nerve. The pain radiated down the front of my left leg. I took prednisone with no relief and then went to 8 physical therapy sessions. It seems that I have gotten worse. Now I have pain in my left hip, left knee and left leg. I can hardly get comfortable in a sleeping position. When I get up from sitting or laying down, I move with great discomfort. After I am up for awhile, I feel like the kinks get worked out but when I sit down, the pain starts again. Any ideas about what could be going on?