Pus in one Kidney. The course of action.

My mother Aged around 58 was suffering from fever since last 1.5 months and initially her blood test shown infection in her blood and urine culture etc. Was normal. With antibiotics her infection has gone but still she was suffering from fever atleast for few hrs. In a day. Last week she started facing pain in one side of her back and her blood test reflected increase in urea and creatinine level. Her ultrasound, CT Scan and blood test reflected problem of PUS in one kidney and she was put on medicine but she is not getting any relief infact with medicine immediately she is suffering from nausea and abdomen pain. Doctor has told us it's normal for person having BP issues and diabetes but her condition is not improving despite of medication. Kindly guide me for future the course of action.