Hi,
How are you? Aside from the pain,are there other symptoms present? It is good that the tests done were normal. How about imaging studies like ultrasound or CT can? This could be due to musculoskeletal, gastrointestinal and urogynecological issues as well. Irregular bowel habits, infection, muscular strain and even spine issues like scoliosis may be the cause. Your medical history and complete physical examiantion are important. Take care and do keep us posted.
please type full list of your symptoms..