Chemical Sensitivity?

I am 24 and have been picking since elementary school. I started by picking the name-tag off my desk, and always had the ugliest desk because of it. Now, I pick my pointer finger cuticles, down to the first knuckle, and my face. I have not done much reading on excoriation disorder but saw that it could be a response? or related to? chemical sensitivity. My body is very sensitive to any chemical entering it: ibuprofen works phenomenal with half the dose, alcohol affects me much more than my peers, any drug really. Wondering if anyone could explain to me how chemical sensitivity relates to skin picking.