I have Oral Allergy Syndrome, verified by an allergist. I am allergic to ALL melons and raw tomatoes. Although I don't have any outward signs. Just the itchy roof of my mouth, itchy, scratchy throat and ears. And my lips & tongue will feel raw and they can get swollen depending on how much I've eaten. The symptoms show up within 2 minutes, usually less. I don't need to eat a lot. Less than a teaspoon full of the offending food. So, if I'm eating at a potluck, where I don't know all the ingredients and can't ask the cook, I eat a spoonful. Then wait 2 minutes to see if I'm allergic to something in the food.
You ate two different kinds of melon AND tomato. Maybe you had a reaction to eating all 3 at once, that became more severe than the usual symptoms?