One of the first classic symptoms of appendicitis is a pain starting near the belly button that often increases in severity, according to MedlinePlus. Other symptoms may include loss of appetite, vomiting, nausea or a low-grade fever.
Appendicitis pain is often associated with the lower right part of the abdomen, but it sometimes starts near the belly button or even higher in the abdomen before moving down and to the right, according to WebMD. As the pain moves, it often becomes sharper. Other pain may be felt in the back or in the rectum. In some people, vomiting begins even before the pain. Other people experience constipation, diarrhea or difficulty passing gas.