is likely only of your sy,ptoms started within the hour of eating the food (and also they do not last that long). However, foods like shellfish do have a lot of histamine
and can release even more histamine if you are prone for urticaria
You can get a skin prick test for seafood (must be off all antihistamines) and is likely to be negative.
What you are having is urticaria, when mast cells on skin release histamine and can be occasionally triggered by histamine-rich foods.
See your doctor for a precription of long-acting antihistamines like fexofenadine
180mg AM 90,g PM plus/minus cetirizine
10mg at luch time.