My period is due on Saturday or Sunday. I had a slight bit of brown cm this morning when I went to the loo and wiped. Haven't really had much since, even when I wipe, but I got my BFP today (a CB digi which said pregnant) so I obviously am at the moment. Hope it isn't a sign of a problem. I've read that it's common to have brown CM which is just old blood flushing out apparently. Maybe this is what is happening to you.