In some people, the pain from IBS can be very severe and even mimic appendicitis. There are several ways to tell if you have acute appendicitis and need immediate medical attention . The first is that the onset of abdominal pain is often abrupt and centred around the belly button. Other signs of acute appendicitis are: Worsening pain that moves to the lower right part of your abdomen Pain that worsens with movement or coughing Loss of appetite Nausea Vomiting Fever Chills