Hello and hope you are doing well.
An allergy testing may help to confirm this. Otherwise its difficult to say. Consult an allergy specialist. First he may do a blood IgE levels to see if they are raised. Next, he will do skin testing. This test is painless, in which a very small amount of certain allergens are pricked into the surface of the skin. If he has allergies, just a little swelling will occur where the allergen was introduced. Reactions occur within about 15 minutes. If needed more sensitive intradermal tests will be used in which a small amount of allergen is injected within the skin.
Hope this helped and do keep us posted.