It must be so frustrating and worrisome to have the back pain flare up. I had some back issues prior to surgery and my doctor made certain I understood that while the hip surgery might alleviate some of the pain if it were hip related, it also was likely that I would continue to experience my previous back pain. He also noted that it might feel worse at first due to all of the surgery related trauma and swelling in the area. He was correct on all counts. The hip replacement definitely resulted in some improvement of my back symptoms as well as my hip and severe leg pain. But certain activities and position still produce back pain, related to my previous issues. Often gentle stretches or certain exercises will help. Just as often, resting and either a hot bath or ice and acetaminophen do the trick as well. If you continue to experience the sharp pains and are worried, maybe you should check back in with your doctor. Perhaps a phone call would offer you some reassurance or direction on what to do about it. Take good care.