What causes expulsions to come out of your pores and leave your skin white splotchy patches ?

Probably a comedo: A comedo is a clogged hair follicle in the skin. Keratin (skin debris) combines with oil to block the follicle. A comedo can be open (blackhead) or closed by skin (whitehead) and occur with or without acne. If you are extracting the debris, then there can be a little temporary injury that leads to the white splotchy patch. If it doesn't clear up, see a dermatologist. Good wishes:)