You may be ovulating late. Do you know when in your cycle you ovulate? Sometimes women ovulate right after their period, sometimes in the middle (average) and sometimes late, just before their period. You may just be ovulating late. If you had appendicitis you would KNOW! You'd have severe pain, a high fever, and vomitting. Don't worry about appendicitis. You're either ovulating late, or you could just be experiencing different symptoms of PMS. Are you bloated? Sometimes PMS brings about pains in and of itself. Not to worry. Try a heating pad, a warm bath, ect.
Also, is there any possibility of pregnancy? If you "could" be pregnant - you may want to take a test. Sometimes in early pregnancy women experience round ligament pain that can extend up to the ovaries. This is normal. If, however, you have a positive pregnancy test and experience any bleeding or spotting along with this type of pain, you might want to call your doctor or head to the emergency room. While this can be normal, sometimes it's indicative of an ectopic (tubal) pregnancy, where a fertilized egg implants into the fallopian tube rather than the uterus. That is always an emergency - but if there is no possibility of pregnancy, or if you don't have a positive pregnancy test, you have nothing to worry about.