Gallstones - MayoClinic.com

Gallstones - MayoClinic.com: "Like many people, you may have gallstones and not know it. In fact, gallstones - solid deposits of cholesterol or calcium salts that form in your gallbladder or nearby bile ducts - often cause no symptoms and require no treatment. But some people with gallstones will have a gallbladder attack that can cause symptoms such as nausea and an intense, steady ache in their upper middle or upper right abdomen. In some cases, the pain can be severe and intermittent."