Abdominal pain and rash; how to manage?

A 34-year-old female presented with recurrent episodes of diffuse colicky abdominal pain. She also has an urticarial rash, flushing, and profuse sweating. Bouts of non-bloody, watery diarrhoea accompanied the abdominal pain. No identifiable trigger was identified, and there was no association with a specific food type allergy. She denied any weight loss. On presentation, she was afebrile, normotensive, and slightly tachycardiac. Her abdomen was tender to palpation. Her pelvic exam was normal. She has had a similar episode in the past; the most recent being three months prior, which was also associated with an itchy rash and abdominal pain and diarrhoea.

What are your thoughts about the differential diagnosis in this patient?