What Causes Dark Brown Bleeding Instead Of Periods?

Hi! I would just like to ask some questions since it s been bothering me for a couple of days. I am expecting to have my period on the 11th of this Month, (August 11). It did come, yes (in fact this is my 5th day today) but it was little and dark brown. I ve noticed there s red blood as well but I m certain that it isn t the same amount of blood I m having for the previous months. I ve been reading articles about scanty menses since Monday so as to ease the tension I m currently feeling. If this is implantation, it should ve lasted only for a day, right? But since this is my fifth day as I ve said earlier, what do you think it is and what should I do?