Hi, I have had bad burning lower back pain (not muscular) for the last three weeks or so. Quite honestly I put it down to hormonal stuff initially but my urine started to get rather cloudy and strong smelling so I thought I should check it out. There has been no burning as I urinate, but the pain and a feeling of pressure just started to be really bad. So I called the GP Tuesday and the receptionist said to drop a sample in. I did and heard nothing. When I called yesterday morning they said I had an infection and to pick up the prescription for antibiotics. I've been given a 3 day course of Trimethoprim. I'm a bit worried that the infection is my kidneys rather than a UTI as the bad pain in my back, is a 3 day course going to clear that? I'm also on Metformin (for Polycystic Ovarian Syndrome) and I've heard metformin can be harsh on kidneys. Should I go back to my GPs and insist to see a Dr? We see due to away in a few days and whilst still in the UK I don't want to be hunting an out of hours service for more antibiotics. Thanks for any advice in advance!