its just called breakthrough bleeding but the main thing is to know the cause of it. my thing is, if theres EVER pain with it.....you get it checked out. because that sounds like what i used to go through and it ended up that i had over a dozen cysts in both ovaries and a polyp in my uterine lining. im not trying to scare you but if that was accompanied by pain that stopped you in your tracks i would call someone. better safe than sorry. and thats such a sensitive part of your body that i wouldn't take any chances y'know?