My xperience with implantation bleeding was that it did not last more than a couple hours, and it never urned into a real flow. It was always light mainly when i wiped. everyone is different though.
i think its just ur period..i had this experience same like urs last year 2days after having sex with my bf..
could just be hormonal. Brown spotting after bleeding or having a period is just old blood left behind. I would just wait it out and if you think that you could be pregnant wait another week and take a test. Usually implantation bleeding is light pink and only visible when wiping.