Review Question - QID 108495

An 8-year old boy with no past medical history presents to the emergency room with 24-hours of severe abdominal pain, nausea, vomiting, and non-bloody diarrhea. His mom states that he has barely eaten in the past 24 hours and has been clutching his abdomen, first near his belly button and now near his right hip. His temperature is 101.4°F (38.5°C), blood pressure is 101/63 mmHg, pulse is 100/min, and respirations are 22/min. On physical exam, the patient is lying very still. There is abdominal tenderness and rigidity upon palpation of the right lower quadrant. What is the most likely cause of this patient’s clinical presentation?