Hello, This is NOT an allergy to seafood but a condition called urticaria. This comes up in red lumps , itchy areas that appear randomly at various parts of the body. Individual hives may disappear in a few hours to within a day but new ones appear. Chicken ,seafood, chocolate can appear to cause an itch as these foods are high in histamine, the exact chemical that causes these urticarial lesions to appear. The condition may start with an infection, but proceeds well after the infection has cleared up. Long-acting non-sedating antihistamines like fexofenadine taken once daily along with cetirizine or atarax (very sedative) over 4-6 weeks help. If it recurs, you need tests like CBC, iron levels, thyroid functions to exclude an underlying cause. Thanks.