Brown spots 2 days before expected period

yung brown spot as in isang patak lang kahapon and until now po e di na nasundan, pero 2 days before expected period yon nangyari at nagpt din naman po ako nung isang araw (3 days before expected period) negative naman po. Possible po ba na implantation bleeding yon?, kahit protected (condom + pull out) po kami last aug 20?