My son gets the exact same thing. He is almost 2, and he has only gotten it with a few things, mostly dipping sauces (ranch, ketchup, bbq sauce) so maybe there is a preservative or something in them that causes this. He doesn't swell up or get any breathing problems, just red where the sauce was. I just wash his face and it goes away in a few minutes. His twin sister doesn't seem to get it tho, at least not that I've ever seen.