Thanks for your query.
Yes your doctor rightly said that this is an allergic response
. This response is known as acute urticaria
that is giving you this red painful swelling on exposure to chocolates. What you have to do to prevent yourself in taking these chocolates further. You may have allegra
150 mg or atarax
25 mg once daily for 7 days. Also you can apply zytee lotion over that painful area to releive pain. Consult an allergist and go for allergic skin test and specific serum IgE assay to identify the allergens in the chocolate or food and start immunotherapy may be sublingual immunotherapy
(SLIT) to preven these reaction on further exposure to those allergens.