Whenever DD (who is now 16 months) has tomato (or tomato based sauce) she reacts in a rash on her face (nowhere else). She is fine with other acidic foods so we know this is a sensitivity to tomato (but not an actual allergy). My DH's Grandma is allergic to tomatoes so we weren't surprised when DD reacted. Allergies to tomatoes are very uncommon but not unheard of. Perhaps wait until DS is a bit older and try again. If he is reacting to tomato, be careful with other acidic foods such as Orange, Pineapple, and Kiwi Fruit - they can have similar reactions. We found DD was ok with these though.

HTH

MG