Oh dear, he's at that age, isn't he? Too old to continuously monitor, yet not old enough to totally trust his judgement.
Remind him the symptoms for a reaction. This is a good opportunity to go over his allergy action plan.
Strawberries are naturally high in histamine and can cause hives, even if not allergic. But the stomachache is a *definite* symptom.
Perhaps this would be a good time to show him the last couple of entries in the "In Memory" thread...just to drive your point home a little more.
Take care,
Daisy