For fifteen long years I was allergic to shellfish. Started with a few hives, and got worse from there. That was that. But then a couple months ago I got a reaction to penicillin and decided to visit the allergist to see what was what. Scratch test for allergies. I had high hopes that maybe I wasn't allergic to shellfish any more. But my arm got red. Really red. It got itchy. Really itchy. Hives.