What Causes Right Sided Body Pain Radiating To Back?

Hi, my wife has been having pain on her right side, this pain radidates to her back. Her Dr. Gave her a clean bil of health for Kidney problems, the blood work also cleared this problem. Also they gave her a sonagram, no stones. She was on antibiotics for a couple of weeks, the pain seemed to calm down, no ab for about three days and the pain has returned very badley. What else could be hhurtig her?