After I had my last (normal) periods, I started taking BCP from the first day of the period. Now, after 3 days from my back end, I've started bleeding, but it is more of brown discharge. I'm confused if this could be implantation bleeding since the timing of bleeding falls at 8-10 days of having sex also. Though we also used protection, I'm confused if this is withdrawal bleed or implantation bleed? Also please let me know if I intend to take a urine test to check, when should I be doing it?