I Am Spotting 19days After My Period, N I Have

i am spotting 19days after my period, n i have been spotting for 5days now , am a bit worried coz i dont know whats wrong with me, am not having any cramp or abdominal pain n i dont have to use sanitary pad either, just tissue, the blood colours red then turn bronish-black later on the tisssue, please when will this bleeding stop and what exactly is wrong with me