Has the possibility of a food allergy been considered? I would definitely look into it. Gluten intolerance is on the rise significantly over the past few years. Try eliminating gluten and see if it shows any relief to her. Sorry about the situation. I think a colonoscopy and endoscopy should also be done too to make sure nothing else is going on.
There are some abdominal vein compression syndromes that will cause intense constant abdominal pain. The most common one is one that I have called May-Thurner Syndrome (lower left abdominal). It's where my left iliac vein was being crushed between my spine and artery in my abdomin. Another one is called Nutcracker Syndrome (upper left abdominal). Someone I know has both of these conditions and has constant abdominal pain. I just wanted to make you aware that these conditions exist as many doctors seem to know very little about them and they often go undiagnosed.
Since your daughter has constant stomach pain, obviously something abnormal is going on there. Did the doctor carry out any further tests beyond urinalysis, such as MRI, ultrasound, and blood tests? If this doctor is a dead end, another doctor should be consulted.