Why does my face get shiny and oily once i wash it or use a cleanser?

i am 13 and i have mildish acne and once i wash and dry my face it looks shiny, and a few hours later it gets oily and greasy. washing with a cleanser makes it more shiny than without a cleanser. i have tried aquafresh toothpaste and colgate for the acne, but nothing happened. i even tried oatmeal to dry out the oily parts but nothing happened either!!! ah its so annoying!!! help?