UGH! I have never had a kidney stone, but my DH has had them twice. He also gets terrible back pains when he has them and has even asked me if I kicked him in the back while we were sleeping because it was also really tender to the touch. He describes them as super painful. For him, he would also have to pee A LOT or feel like he needed to every few minutes. It also made him nauseous. Are you having any other symptoms besides back pain on the left side?
Glad you are getting in to see a doctor tomorrow and hopefully they will be able to shed some light on what is causing you pain. I hope you feel better soon!