What Treatment Is Recommended For This Ultrasound Test Result?

Hi, I have been having back pains, mostly at night and mostly on the right hand side for about 3 months now. I have been for an ultrasound which showed a slightly larger right kidney and urinary retention. I also showed with blood and pus in my urine. SInce then I have been treated with 2 different types of anti-biotics but the blood and pus are still showing. Also, they can t seen to grow a bacteria from it. Can you give me any answers at all? Or something to look into?