Only one slight possibility as far as I know. I made some microwave popcorn on Wednesday evening. It was a brand new box of Act II butter. I’ve used it before, but haven’t had it for a couple of years. ???
As far as where the hives are... everywhere. The itchiest ones are on the back of my head (in my hair) and the areas around my chest. The ones on my upper arms are solid in an area about 5 x 3. Otherwise, I have areas of blotches. Also, on my legs and feet, they look more like individual hives about the size of peas.
PS: Forgot to mention my hands. They are very itchy and swollen. Had to remove my rings with the aid of cold water and my fingers hurt to bend them.