That's very interesting Jack. He may well be allergic to a whole range of things.
I had thought of suggesting he gets one of those allergy tests at the doctor's, where they put lots of different stuff all up your arm then see if a reaction occurs.
The thing is he lived in a totally different environment for the early part of his life, and had never seen bread, potatoes, flour, no trees around at all, no flowers or bees, no agricultural crops, no butter, milk or dairy foods. He may well be reacting to those as well as the pollens.