How old are you? Have you been on Steroids (not the body builder kind), either in pill form or Steroid injections for back pain maybe?
I ask because this kind of medication can cause Avascular Necrosis of the Femoral Head, which can cause the symptoms you describe. Another explanation may be just arthritis-without knowing your age, I cannot guess whether the arthritis is Osteoarthritis, or perhaps another type, like Rheumatoid Arthritis.

