After it is formed, the stone may stay in the kidney or travel down the urinary tract into the ureter. Sometimes, tiny stones move out of the body in the urine without causing too much pain. But stones that don't move may cause a back-up of urine in the kidney, ureter, the bladder, or the urethra. This is what causes the pain. Possible causes include drinking too little water, exercise (too much or too little), obesity, weight loss surgery, or eating food with too much salt or sugar. Infections and family history might be important in some people. Eating too much fructose correlates with increasing risk of developing a kidney stone.