DS1 and mom had just gotten home from a dinner with classmates. They left early because he was throwing up. Lots. A few hives, runny nose, and more throwing up. It was a weekly dinner and we had packed him a lunch, like we always do. We thought it was because he drank from DS2's reusable water bottle, which he may have cross-contaminated with something.
Turns out it was the fusilli in the lunch we packed him had "pasteurized egg whites" as an additive at the bottom of the ingredients. Oops.
Thank goodness he'd only eaten four pieces of that fusilli by the time he noticed something wasn't right. Imagine.
At least we know he's not so reactive as to get sick from the unlikely cross-contamination of a shared water bottle.