What is Appendasidus?

Did you mean appendicitis?

If so, then Web MD has a good article on it:

"Appendicitis is an inflammation of the appendix, a 3 1/2-inch-long tube of tissue that extends from the large intestine. No one is absolutely certain what the function of the appendix is. One thing we do know: We can live without it, without apparent consequences. Appendicitis is a medical emergency that requires prompt surgery to remove the appendix. Left untreated, an inflamed appendix will eventually burst, or perforate, spilling infectious materials into the abdominal cavity. This can lead to peritonitis, a serious inflammation of the abdominal cavity's lining (the peritoneum) that can be fatal unless it is treated quickly with strong antibiotics."

According to http://digestive.niddk.nih.gov/ddiseases/pubs/appendicitis/ ,

Most people with appendicitis have classic symptoms that a doctor can easily identify. The main symptom of appendicitis is abdominal pain. The abdominal pain usually * occurs suddenly, often causing a person to wake up at night * occurs before other symptoms * begins near the belly button and then moves lower and to the right * is new and unlike any pain felt before * gets worse in a matter of hours * gets worse when moving around, taking deep breaths, coughing, or sneezing Other symptoms of appendicitis may include * loss of appetite * nausea * vomiting * constipation or diarrhea * inability to pass gas * a low-grade fever that follows other symptoms * abdominal swelling * the feeling that passing stool will relieve discomfort Symptoms vary and can mimic other sources of abdominal pain, including * intestinal obstruction * inflammatory bowel disease * pelvic inflammatory disease and other gynecological disorders * intestinal adhesions * constipation"