I've just come off a month period 9 days ago.my breast are swollen and i have mild cramping. what could it be?

Hormones: It appears that you had a prolonged period that lasted 1 month. I am assuming that your pregnancy test was negative. If you have not done your pregnancy test, please do it. This bleeding could be from a missed pregnancy that resulted in a miscarriage. That is why you have cramping and swollen breasts. If pregnancy test negative, it can be related to a changing hormone pattern from last cycle.