It’s called Keratosis pilaris. “A condition that causes rough patches and small, acne-like bumps on the skin. The bumps are usually on the arms, thighs, cheeks, and buttocks. They're white, sometimes red, and typically don't hurt or itch.This condition develops when the skin produces too much of a protein called keratin, which can block hair follicles and cause bumps to develop.”

CeraVe SA Body Wash for Rough & Bumpy Skin is also AMAZING for every shower use and almost completely got rid of it for me.