confused

hey ladies!! quick question! i was supposed to start my period on the 3rd of this month. and i still haven't started, but yesterday morning i started spotting. really lightly, and so i figured it was my period, i used a tampon and by the time i went to go change it i wasn't bleeding anymore, and it was just a tiny bit of blood on the tampon. i went all night last night and all day today with out any kind of bleeding...anybody have any idea of what it could be?