What Causes Acne During Menstrual Cycle?

Hi, i am 23 years old. In my teenage i was not getting acne . but now I use to get lots of horrible acne the time of period . I use to get period on time . but last month I got so pain . And this month my period got delay for more than 1 week. I m getting so much acne also . It is some different kind of . I m getting some tommy also . please say same solution..