Well I am not sure if your daughter has the same issue but my son had a Urinary Tract Defect that needed surgical correction.
When he was six weeks old he got a bad fever. Being a new mom, I was scared so we went to the ER at 3am. They sent us home after a few hours when his fever went down right away after being given tylenol. They didn't do any tests. The next night we were back...I couldn't get his fever to go down at all by that point, and it had even started to climb.
Well, after a battery of tests including blood, urine, spinal tap, and a few other physical exams..he had a bad UTI. We were referred to a Urologist by his pcp. 4 weeks later his UTI was back.
We found out he had a duplicated urinary system on each side. He had double sets of ureters, unlike most people who only have one on each side. One side was ok, it functioned normally. The other causes a blockage of urine because the second ureter drained into the bottom on the bladder, and was blocked by natural tissue formation. Anyways, he had surgery at 10 months (now 17 months). It was a bit scary, but i knew I was lucky because his defect was correctable.
My point is that if he hadn't had that surgery, he would suffer from kidney damage and need part of his left kidney removed. I am not sure if your little girl has that problem, but I think you should do all you can to find the underlying issue here, because no doubt there is one whether it be physical or psychologica.