What Could Continued Pain On Left Side Below The Rib Radiating To Pelvic Area Indicate?

Hi, I ve been having pain on my left side starting just below the rib, down to my pelvic area for almost 3 months now. First a doctor said it was a UTI and gave me antibiotics, I did the treatment and didnt feel better. I then got a culture of my urine done which showed E. coli and took antibiotics for that which didn t help either. There is now pain on my right side and a burning on my pelvic area in the morning. I m having my urine retested and an ultrasound this week, any ideas on what this could be? Could it have to do with an infection in my bowels? Although my bowel movements are fine. The only symptoms I feel are chronic pain and nausea from time to time, plus tenderness in my abdominal area.