Hi Lisa, my DD has had a few urine infections unfortunately. When she had the first one, she was on Amoxycillin for a week which cleared it up, but she also got referred to hospital for an ultrasound scan on her kidneys - just in case it was something more serious. I made the huge mistake of telling her that scans don't hurt - it did, so please bear this in mind if your's has to have one! Luckily her scan showed nothing abnormal.
She has had a few urine infections since, and each time, my GP has alternated her antibiotics (Eg. last time was Amoxycillin, this time Trimethoprim, next time Amoxycillin) Last time was about a year ago, and GP said that if it happens again, she will have to go on antibiotics long-term for 6 months. So far, so good
Hope your DD feels better soon