Spotting ( drop of blood)

Hello, nangyari po ulit 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 bleding yon?, kahit protected (condom + pull out) po kami last aug 20?