Humm very good question. I have been told that they have to be exposed to the allergen to show positive, BUT I really don't know how true that is.
In your case, NO... Do not add any of those things back. I think you pretty much have your answers without even going to the allergist.
Plus, all his could be intolerances (which I doubt), but still. I would hate for you to re-introduce those offending foods and cause his body damage again.
BTW: He is perfectly clear?
So happy for you.
Wendy