Why Did My Menses Recur After 3 Days Of Finishing Normal Menses?

Hi. I'm female at age of 23. My period started 15 of feb and ended on 21 of Feb. then after 3 days. It came again. It's been 5 days now and it is still not stopping! And the blood is not like the normal blood colour like the first time, the second time is more like dark red colour. What can I do with it? Any medicine that I can take to stop it? Thanks