Symptoms of kidney stones. You may not know you have a kidney stone unless it causes pain, is large and blocks the flow of urine or is being passed. The most common symptom is severe, fluctuating pain in the lower back or side under the ribs.idney stones are a formation of hardened minerals in the kidneys or urinary system. In most cases, kidney stones are formed because of a decrease in urine volume or increase in the minerals that form the stones in the urine. About 1 in every 20 people will have a kidney stone in their lifetime.