When should I be concerned about flank pain?

Flank pain is the pain you feel in your side near your back. Sometimes it lasts for a short time and might be from a minor issue, but other times it can be a sign of something serious. You should be concerned and see a doctor if the pain is very strong or comes on suddenly. Also, if you notice other symptoms like a fever, chills, or if your urine looks unusual—maybe cloudy or even has blood in it—it might indicate an infection such as pyelonephritis. Other problems, like kidney stones, can also cause sharp pain that starts in the flank area and moves toward your lower belly or groin. Even in children, unusual causes like nutcracker syndrome (a condition that affects the kidney) have been mentioned. Keeping track of your pain and any other symptoms, and sharing that with a doctor, will help them figure out the right tests and treatment to make you feel better.