Allergies can also occur within a very short period of time after eating and can range from diarrhea, vomiting, hives/rashes, shortness of breath, eye swelling, tightness around the chest and many other symptoms. Eating the wrong thing is generally how I've learned what I'm allergic to. Nothing life threatening but it can last for several hours and has occurred within as short as 1/2 hour after consuming something to 2-3 hours after consuming.
Symptoms have lasted for as little as 2-3 hours and as long as 4-5 days. Sometimes things I'm not generally not terribly allergic to can be enhanced by other things (e.g., another virus I've picked up, normal meal patterns disrupted. travel fatigue, etc.). Some things I'm allergic to only if they're grown in certain areas because of other factors not always easily determined (e.g., allergic to kiwi fruit from California but not if grown in New Zealand, also allergic to spinach but not if baby spinach, at least not usually).
So it could be food poisoning, food allergies, disruption to normal eating patterns, viruses picked up from others, and even differences in mineral content in the local water. That's why I always travel with a variety of OTC medications like Immodium and Pepto-Bismal, Tums, and allergy medications because you just never know what's going to happen when you're away from home and normal routines.