i finally figured it out! i'm allergic to something called imidazolidinyl urea.
i bought a pricey lotion at the podiatrist's office, supposed to help with dry skin much more than what can be bought over the counter. it contains 10% urea, and supposedly, people who are allergic to urea will show contact dermatitis symptoms when they use a product with just 2% urea.
omg . . . i am going to DIE before this lotion wears off.
ends up, urea is a preservative that produces formaldehyde. nice to know that's what i'm rubbing onto my skin, turning myself into some sort of living mummy.