Would it make sense that someone allergic to canteloupe and watermelon would have an allergic reaction to avocados (causing welts on face)? Or would Greek olives cause such a reaction? These are the only two “different” foods ingested. This person is also wheat gluten sensitive.
Cantaloupe and watermelon are related botanically (members of the gourd family). It isn’t unusual to see a reaction to more than one related food. However, avocado and olive are not related—to each other or to the melon family. If he/she reacts to all of the foods, there is likely a specific allergy/sensitivity to each one. Note that avocado is in the same “food family” with bay leaf, cinnamon, sassafras, camphor and file gumbo seasoning, while olives are in a family all by themselves. Ultimately, when dealing with food allergies/sensitivities, it’s the individual’s response to specific foods that is the most important.