Ok are you sure it’s just dry skin? I once had MRSA and it spread to my ass cheeks, itched like crazy and the welts were huge.

Another thing could be allergies to something. I was taking Ozempic to help control diabetes and it did dry out my skin and my legs and ass were always itching.

It also it turned a patch of my skin on my head grey that would constantly flake along with my eyebrows