Yes, yes, yes. I don't really see how it's possible for the allergen to be comingling with your other food and for it NOT to contaminate things. If the shrimp was there as a 'treat' for the holidays, I strongly suspect that this was your "flu" since it was probably present in small amounts on touch surfaces throughout your environment. BTDT.
The reason why only I feed our tropical fish is that I can do it without:
a) getting fish food ANYWHERE but INTO the fish tank (unlike the adult members of my household-- oh, wait-- that doesn't NEED to be plural)
b) contaminating my hands-- because I 'shake/tap' gently, I don't ever handle the food itself, and
c) I keep my face WAY WAY away from that action, and I still wash my hands incredibly well afterwards.
All that to say-- I'm not really all that sensitive to shellfish ( I don't think, anyway-- I don't seem to react to things that are on well-managed shared lines like better-than-bouillion).
The amounts involved are really tiny. NO WAY can I eat food at a restaurant with someone eating a shrimp cocktail within ten feet of me. It smells like vomit or worse, and it makes my food TASTE that way, as well. DH has watched me turn green and ask for a box a few times in a restaurant.