I know that there's some controversy in the medical field about food allergies and histamine reactions, but as I understand it, it's really a definitional controversy. There's no question that many people have histamine reactions to many common foods; immunologists just quibble about whether it's truly an "allergy" in the technical sense of the word.

There's really no downside to just TRYING a challenge diet. It's a hassle for sure, but it will give you valuable information that you really can't get any other way (serum IgG yields lots of false positives, intracutaneous skin prick yields lots of false negatives, monitoring systemic reactions after subcutaneous injection just isn't that sensitive).