I'm Having Pain In My Left Leg Which May Move

I'm having pain in my left leg which may move from front below the hip and above the knee to the lft side of my leg below the knee and down to my foot and can even be more tah one place at a time. It is difficult to get comfortable sitting for any length of time and sleeping is difficult. I am losing a lt of sleep with this ailment. I am being treated at PT and am heading today for my third visit but am not seeing good results. Doctor has prescribed medication including prednisone 20 mg., oxycodone /acetaminophen 5-3.25 mg.and I have tried muscle relaxaxant cyclobenzaprine as well. Can you make any prediction what is causing this?