Brown discharge week before period.

Every month, the week or so before my period I'll start to get a brown discharge that will last until I get my actual period. My period is due in 6 days and the discharge started a little bit yesterday and more noticeably today after sex. I'm not sure if this time it could be implantation bleeding because it looks a little bit more pink or if it's still just the same as every month. My main question is, does anyone else experience this and have any explanations as to what it could be? Thank you!