My Daughter Fell Off A Bucket On Monday. She Hit

My daughter fell off a bucket on Monday. She hit pretty hard. At first she thought she might have broken her butt bone. Since then she has had low back pain. She started complaining of not urinating very much on Wednesday and Thursday. By Friday she was urinating more than usual. The RN is dark and has a strong sent to it. I took her to an urgent care and they checked for urinary track infection. It was a rapid test and they said that its not always accurate. It came back negative but her prescribed Macrobid for her anyway. He said all the culture that he said would be in by Thursday. She's feeling very fatigued and in quite a bit of pain. I'm just thinking maybe it's not a urinary track infection maybe, her fall has caused other problems.