Confused

My breasts have been hurting for about three weeks now. I got AF 3 days ago, but it was alot lighter than usual and just some cramping and its already gone. (Normally I have cramps so bad Im in tears, and AF is really bad for 7 days). I dont use any kind of birth control. I dont really think Im pregnant but i dont know whats going on. And why my breats have been hurting so bad for so long.