What Causes Blackish Fluid Discharge From Vagina In An Anemic Person?

Hi I m a 44 year old woman who has never had a heavy period and it only last around 1 till 2 days I m also enimic have been for 16 years docs had done everything but this month my period has been over after day or two but when I wipe myself after go to the toilet it s like a black colour any ideas what could be causing this