My DD is 7 and for years and years has complained of stomach aches and headaches. I've never acted on it as she seemed okay otherwise - no fever, other signs of illness, but the childminder brought it up and it made me realise I should have looked into it ages ago.
DD gets stomach aches after or sometimes during eating. She is not a fast eater at all, so it's not that. She has always disliked and avoided cake, biscuits and bread and doesn't like butter. Recently she started eating a different breakfast cereal (an oaty granola) and although she loves it she ends up doubled over with cramps. Obviously I've stopped her eating it now. She occasionally gets hives after eating but that seems related to tomatoes not cereals or dairy.
I've booked an appointment with the doctor, but in the meantime, not sure what to think or do.