ve spread to cover my entire chest, upper arms(down to short sleeve length), and upper back pretty solidly. This past week, its spread to my lower
back and upper butt,
and the top of my stomach. I went to a dermatologist, and he diagnosed me with prurigo, gave me a prescription for some cream and told me to use sarna. Didn't explain what it was, nothing, so I looked it up when I got home - I do not believe that is what I have.