A 52-year-old man presents with abdominal pain, intermittent nausea, and three episodes of vomiting over the last two days. There is no history of fever; respiratory, urinary, or gastrointestinal symptoms; or abdominal trauma.

He had an episode of severe epigastric pain radiating to the back around two months ago, which required emergency admission and hospitalization for a week. No medical records are available. He recalls that he was first kept nil per oral and given intravenous fluids; and then progressively changed over to semi-solids and then solids. He is unaware what medications, if any, were administered. Since then, he has experienced intermittent epigastric discomfort.

His medical and surgical histories are otherwise unremarkable. He is not on any medications currently. There is no history of allergies. He does not smoke, but has been a heavy drinker for over a decade. A full blood count and c-reactive protein are both within normal parameters.