I get the same sort of things - raw tomatoes bring my skin up in an itchy, blotchy raised rash, but oddly I can eat them with no problems and cooked tomatoes are fine. I only remembered this allergy when he-who-must-be-obeyed developed a cherry tomato fetish (how many are too many in a babies daily intake ?) and dealing with the fall out zone of this. I'd just knock off tomatoes for a bit and then retry - it doesn't mean that she'll necessarily react to anything else or that it'll get worse. I'd try rubbing a bit of tomato onto her arm first to see whether she reacts there rather than feeding it to her, just in case though. This type of reaction is called urticuria if you're interested.