I eat shellfish often, and without any side effects most of the time. Once in a blue moon (every other year or so) I get a head to toe rash after eating crab, scallops, lobster.... It doesn't itch and it goes away after a day or two. Is this ever anything to be concerned about? Why doesn't this happen every time I eat shellfish? What is it about that particular piece/meal triggers a reaction?
Thanks in advance!