First, it likely is not a kidney infection as kidney pain would occur in either side of your back, since your kidneys lie in the back part of your abdominal cavity. Secondly, you would be surprised the pain that something as simple as gas can cause. I was once told by my doctor that gas pains have had a few of her patients consider going to the hospital before. Take 2 gas-x and wait a few hours I bet you’ll be good as new! :) hope it helps