The appendix is a small, finger-shaped pouch that protrudes from the colon on the lower right side of the belly, also called the abdomen. When someone has appendicitis, the appendix becomes inflamed and causes pain in the lower right abdomen. However, in most people, pain begins around the belly button and then moves to the lower right side of the abdomen within hours. Pressing on the lower right-hand side, coughing, or walking may all make the pain worse. If you are experiencing abdominal pain thats gradually getting worse, contact your GP or local out-of-hours service immediately.