I have thigh pain at night usually after I have been asleep for about 5 hours. Its severe enough to wake me up. It is on the outside of my left thigh, a burning sensation and sometimes goes down my leg. This has been going on for quite some time, a few years. If I lay on my back it stops hurting or if I get up and move around it temporarily stops hurting. When I walk or lean on that leg it hurts a bit but not as severe as at night. What could my problem be?