Spotting....?

My boyfriend and I have sex a lot. We started the pull out method almost a month ago. I am on my first pack of birth control. I started spotting brown on Sunday. It continued as light spotting until last night, it got a little heavier. My boobs hurt and I've been having cramps and doing nothing but sleeping. Anyone know what is happening?

Update: it is still brown but now there is blood as if it is my period when I wipe. My period isn't due for at least a week because of where I am in my BC pack.