Flank pain refers to discomfort in your upper abdomen or back and sides. It develops in the area below the ribs and above the pelvis. Usually, the pain is worse on one side of your body. Most people experience flank pain at least once in their life, and the discomfort is usually temporary. However, constant or severe flank pain may indicate a serious medical condition, such as dehydration or a urinary tract infection. Kidney stones or another kidney problem may also cause persistent flank pain. Though flank pain is often a symptom of a kidney problem, it can also be the result of other medical conditions if it occurs along with additional symptoms. It’s important to see your doctor if you have chronic or severe flank pain, especially if you’re also experiencing other symptoms. causes may be kidney stones,bladder infection. thank you.