What caused my adult-onset allergies?

I am 48 years old, and have never been allergic to Iodine, but just within the last few months, I have developed allergies to iodine as well as alot of the preservatives in some foods. I have always had allergic reactions to something, allergist said it is just a combo of things in my body. That really helped alot.LOL. I keep liquid Benadryl as well as an Epi-Pen with me at all times. I love shrimp and seafood, so I sometimes just take my chances. Usually the Benadryl will take care of it. I have a friend that had always eaten seafood, and three years ago, she ate it and wound up in the hospital for three days. Now she can't have anything with it in it. It as always possible to necome allergic to anything, no matter whether you have ever had a problem or not. GOO LUCK!!!!!!!!!! I love my cats, so I don't know what I would do.