Urinary stones are hard crystals that form anywhere along the pee system—kidney, ureter, or bladder. When they move, they send out sharp, unmistakable signals. The headline is sudden, severe flank pain. It feels like a knife in the back just below the ribs and shoots into the groin as the stone travels. Nausea and vomiting often ride along. The gut shares nerves with the urinary system, so the pain triggers a sick stomach. Blood in the urine is common. The stream may look pink or tea-colored, and the blood can appear even when pain is mild. Urinary changes show up... Learn more