What Causes Continuous Blood Discharge From The Vagina?

i am 16 years old and sexually active i have always had irregular periods when that time of the month was coming around about a month ago the blood was brown it is usually brown at the end or beginning of my period but this time it stayed brown my period should have been over after a couple days but i am still releasing brown fluid from my vagina i don't have any pain its just annoying it like I'm having a light brown period everyday it has been going on for about a month now