Hi Dr. Rynne, I have been having extreme lower left back pain for the past three days. Ii have had a history of kidney stones and thought it might be that again. I went to a walkin clinic today and they took a urine sample. They found no signs of blood or infection in my urine and gave me no explanation for my pain other than I must have strained a muscle. I don t believe this is correct. Any other options you can think of.