What Could Be The Reason And What Can I Do For Chronic Neck Pain ?

I ve been having horrible neck pain for over a month now. Cannot get comfortable to sleep. Worse in the morning and evening. Also pain in my thighs and knees. X-rays showed nothing abnormal. No pain/tingling in my arms. Only thing that has helped with the pain is Prednisone. Wake up every morning with a terribly stiff neck , shoulders and headache . Slowly improves (but not completely) throughout the day, starts up again in the evening and keeps me awake at night. I ve already tried changing my posture, sleeping in different places with different pillows. I tried every OTC NSAID and they didn t touch it. Dr. prescribed Prednisone which is the only thing that actually worked! What could it be if my tests are normal? History: I have TMJ which also causes me occasional pain, but not this bad.