Hip Pain

Ever since I can remember my hips (particularly my left one) has popped, clicked, cracked, snapped-- whatever. Ever since I turned 25 though (I'm 28 now), I cant hold my hips at a 45 degree angle (for sex, or sitting funny) for longer than a min or so without having excruciating pain plusate through my left hip. I went to the doctor a few years back and she signed me up for some physical therapy. It helped a little, and general exercise and movement helps keep those hips from going stiff on me... but if I don't exercise for a day or two the pain comes crawling back... I guess I'm wondering if anyone else has this issue of hip pain as it relates to sex and how you deal with it... its certainly a libido crusher.