What Causes Low Vaginal Bleeding During Period Post Abortion?

i ad an abortion march 6th and ever since then my peiod hasnt been normal and it was every light ever since now liquid brown stiff is comming from my virgina and i hAVE HAD SEX A COUPLE TIMES BEFORE MY PERIOD BU E AND M BOYFRIEND ALWAYS USE A CONDOM IM SCARED OF IT BEING SOMETHING BAD WHAT DO I DO?