What Causes Painful Breasts After Menstruation?

Hi I'm 25 years old and my breasts have been hurtting really bad latley. I am on birthcontrol and I take them to the t. But it get worse when I take my bra off. I have two kids already so I know it kinda feels like as if I was but I'm not checked but I need to know why they hurt so bad. It started after I got off my monthly. And has not stoped