I have the same problem so when I lay on my side I put a pillow or two between my knees...this helps take pressure of the hips. I had an accident when I was a kid, hit by a car, and still have problem in adulthood (don't want to say my age, lol). It may be from a nerve or bone, the only way to see is to have xrays done, to rule out bone issues, and an M.R.I to rule out fibrous issues. Try the pillow idea tonight and see if it helps. Good luck from a fellow sufferer.