X-rays do not always show the cause of pain - nor do mri's etc - sometimes the pain in say your hip can be caused by something elsewhere being out of position or by a nerve being pinched or a muscle problem. This applies especially if you're female & had any children - we tend to carry them & other stuff on our hips & so put things "out" & cause problems later.

Try some of the natural meds like chondroitin & glucosamine 750-1500mgs of each once or twice a day - there are others too.