Kidney/side pain?

Ka

Last night I woke up with an ache on both sides of my lower back, it feels like where my kidneys are. Today it's still a dull ache. Has anyone else experienced this? I'm going to my doctors tomorrow for a flu shot so I'm going to tell them so they can rule out a UTI, but just wondering if anyone else has felt this way. Its not unbearable but it's very uncomfortable and hurts to put pressure there.