<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been experiencing pain of the anus, upper abdominal pain, and vomiting. What could be wrong with me?  <response>: Based on your symptoms, it is likely that you are experiencing ileus, which is a condition in which the normal movement of the intestines is absent or severely reduced, leading to painful abdominal distension, nausea and vomiting. 