Do not ignore sharp pain in your side

If you feel as if you're being skewered in your right side, and you're also nauseated and running a fever, you could have appendicitis. For women, another possibility is an ovarian cyst.

Typically these fluid-filled sacs are harmless and disappear on their own. But if one twists or ruptures, it can cause terrible pain.

In both cases, you're looking at emergency surgery. “If you don't remove an inflamed appendix, it can burst," says Lin Chang, MD, a gastroenterologist and co-director of the Center for Neurovisceral Sciences and Women's Health at UCLA.

A twisted cyst also needs to be removed right away, as it can block blood flow to the ovary within hours.