Went to the doctor Monday with back pain. Figured it was a UTC. I was told there was a little bacteria in my urine and she treated it as a UTC. I am on antibiotics and will get up to check the name. Last night I noticed my left kidney area (I think it my kidney area - left back - under ribcage) felt numb. It went away for a few hours, but is back. Do you think I should to to ER?