Reacquiring abdominal pain.

My 13-year-old daughter has had reacquiring abdominal pain for the last few years, right side in the appendix/gallbladder area. The pain seems to travel and can spasm. It is becoming more painful and frequent. She has had no problem with her bowels or her menstrual cycle. We have had urinalysis, blood test, and ultra sound, all have checked out fine. We are scheduled for (excuse me I have forgotten the name of the test) a test that checks the function of the gallbladder by the injection of radioactive material. My daughter feels frustration and that people think she is faking the pain. I know she is not. Has anyone else had this experience? Thank you for your response.