Abdominal Pain And Incrases While Coughing,laughing, Diarrhoea, Lowered Apetite

My daughter has had upper right quadrant abdomen pain for about 3 weeks. It is very tender to touch especially to the right of her navel and she is only 15 years old. She has ad a CT scan , X-rays, blood work, urinalysis , and ultrasounds and everything comes back fine. She does not have a fever. It worsens or has sharp pain when she moves a certain way, coughs, laughs, hiccups, anything jarring. She reports some diarrhea but not constant, but she has a lack of appetite and is tired because she doesn t sleep well because if she moves in her sleep the pain wakes her. Now her pediatrician wants to send her to a pediatric gastroenterologist . Would they be able to diagnose tendonitis to the diaphragm? Could that be it? If so, how would it be treated? I have been so concerned it could be appendicitis but the tests don t seem to be giving the answer.