Why is it that my face will be clear before my period but then after my period i break out again really bad ?

Hormones. : Menses occurs due to drop in hormone levels. With your new cycle you start to have the rise in hormone levels that lead to ovulation and your next period. By suppressing ovulation and keeping hormone levels stable you can reduce acne. It's a little bit more complicated than that but that's it in a but shell.

Hormones: May be your hormones. Right before your period your body's estrogen/progesterone levels are dropping, during the period they are at their lowest levels in the cycle. Right after your period your body is increasing it's estrogen production, but it's not at it's highest point at that time. It may be your skin is sensitive to these hormone changes. Ocps are one of the first line treatmts for acne.