My DS2 (aged 5) has a dairy intolerance to lactose and CMP.
Last year he informed me ketchup made him feel funny so stopped having it. No biggie as it's not something used much.
But last week he said his mouth felt funny after eating some pasta which had chicken in it with a tomato pasta sauce. His lips were swollen so gave him an anti-histamine. Didn't really think anything about it as he had a bit of a cold and and thought it was that ( I know..stupid me...)
The same has happened this evening with a chilli I made ( full of tomato puree and a can of chopped toms).
Yet he had baked beans last week and was ok with that and cherry toms...