What Causes Severe Pain Around The Kidneys Along With Fever?

Hi, I had severe pain in the kidney region, fever, sweats and very raised blood pressure recently. I am normally very healthy and eat a very good diet with no alcohol. First visit to my doctor said no virus and refused me antibiotics. A week later I felt very ill and second visit to doctor resulted in a reluctant prescription of co-amoxiclav. These made me feel better but the pain in the kidney region became worse and a third visit to the doctor resulted in no treatment due to urine tests coming back negative for everything but blood. A fourth visit resulted in my request for citroflaxin (5 days) being granted, which seemed to resolve the problem. Now, 10 days later, I have stomach pains and light coloured poo. Do you think its due to the strong antibiotics or is something else going on? Have I suffered internal damage due to the failure to prescribe antibiotics initially?