Hi there, I had severe pain in my back on the left side for a little while. We figured that it was a kidney infection and my doctor put me on a medication called cipro for 7 days. It has since gone away. I would check with your doctor but mine said at first that it could be a kidney infection or an UTI. both have the same pains. Do you have problems urinating? That could be a sign of a UTI. I didn't have any pains but the one in my back and it just kept getting worse till I saw my doc. Good luck.