Well, it's obviously not in her head, it's in her stomach. It's quite unfortunate when dr's tell their patients this. It simply means that they don't have a diagnosis, but that doesn't mean the pain isn't real. I have Celiac disease, and the diarrhea problems sound like that. You can have false negative tests for it, but I am not sure if her complaints really fit that picture.
I'm not sure-did she have a hida scan to test for gall bladder emptying? This would not be something an ultrasound can check for. I had my GB out and had increasingly horrible problems afterward. The tests they did afterward showed that I was suspected to have spasm of the sphincter of oddi-a spasm of the common bile duct. Instead of treating this with western medicine (I too have had about a million dollars worth of worthless testing done as well) I decided to try acupuncture. Oh my goodness, what a miraculous difference it made in my life. I seriously wanted to die prior to this. it took about 6 months for the attacks to stop. I have one every now and then, but have really good pain medication to take when they happen. Stress seems to affect this problem considerably. I hope that this information helps you in some way. Sometimes a departure from western medicine is oin orser-especially when they say "its all in your head" Seriously, why would anyone WANT to feel like that??? It's pretty frustrating and makes the patient feel like they are crazy or soemthing. Doctors don't like to admit they don't know something and I think this is their way to get around having to do so, at your expense.
I hope you and your daughter find answers.