B.S.
Consider foods with a tomato base and don't forget that pineapple is a citrus, too. It's in a lot of your canned and frozen mixed fruit combinations. My daycare kids love canned madarin orange slices; but I have one child who cannot tolerate them. I'm wondering about eggs and even peanut butter.
It's obviously something that's been going on each day for a week...could very well be teething if he's working on molars.