Nearly one million Americans are diagnosed with gallstones each year. These stones are made of bile salts, cholesterol, and other substances. If a gallstone becomes lodged in your bile duct, you might experience an attack of severe pain under your right shoulder, between your shoulder blades, or in your upper abdomen. If you experience pain that lasts more than five hours, or you have a severe stomach ache accompanied by vomiting and fever, seek medical attention.