You may have developed an allergy. I developed an allergy to prawns when I was 20! I had peeled and eaten prawns my whole life and then on Christmas Day one year when I was 20 I broke out in such terrible hives and was all puffy immediately after peeling the prawns; then the next time the same thing happened.. Now I can't even touch prawns! (Very sad as I love prawns!)

As PP said I would write down everything you have had to eat and work backwards from there.. Test certain foods and see if you have the same reaction.

I found a lot of relief using camomile lotion! It soothes the itch..