Open Question: Please shed some light on my situation.?

My 16 year old daughter has been suffering from constant abdominal pain for a few months now. It never goes away and is draining all of her energy. She is stressed out and it is beginning to stress me out as well. The doctor told her there is no physical illness. He said that it is stress related and if she adjusts her diet and lifestyle it will get better. However, she does not believe this