What Causes Recurring Abdominal Pain In Lower Right Quadrant?

A week ago I was awakened with severe abdominal pain in the LRQ. I was instantly nauseated and sweating. I thought it was my appendix and went to the ER. They did several test and it showed no kidney or gall stones, appendix, ovaries unremarkable. They only found a UTI and sent me home with an antibiotic. Last night the pain came back, but it was in waves so I held out for the doc office to open. Now the UTI is gone, and no explanation for the pain. Body temp 97.4. Both times I had slept on the right side and was awakened. It feels like kidney pain but they say no stones were found.