She could have kidney stones. She needs to see a urologist and find out what's going on.
As your daughter has finished her antibiotic, she still may have an infection or a blockage like kidney stones as mentioned by Caryopteris.
She needs to go back to her doctor and take a urine specimen with her. The doctor can arrange for a blood test to check her kidney function and also send your daughter for a ultrasound scan and referral to a urologist if there is a problem still with the kidney or confirmation of a kidney stone.
Stones can be extremely small like a grain of sand or much bigger. But they do cause pain and discomfort when they start to move and can cause recurrent kidney infections as they damage the inside of the urinary tubes as they move.
Your daughter may experience pains in her tummy like wind, this is called renal colic.
Whether your daughter still has an infection or a kidney stone it is important that she drinks a lot of water. 2-3 litres per day is recommended, a bit more if she is sweating or working out.
The reason for the water is to help flush out any bacteria and also help to move the stone (if she has one). Be aware that if a kidney stone is confirmed, that it can take months for it to finally come out. Sometimes, they do get stuck in the urinary tract and medical intervention is required to remove them.
Tell your daughter to urinate into a receptacle so that she can observe the urine for any sediment, stones, visible blood, cloudiness and smell. Very strong smelling urine like offal, can be an indication of kidney problems. A cloudy urine can be an indicator for infection.
It take two days for the antibiotics to work so she should be feeling better. As long as she is drinking plenty of water it should have started clearing up by now. It is very important to flush the kidneys out very well if you have an infection. Not drinking enough even while on antibiotics will not help flush her kidneys out. Her pain may also be from straining to urinate or frequent urination. If she is not better by monday she should go back to the dr and make sure there is nothing else wrong. Best wishes, Sissie