Got my BFP but still spotting

I got my BFP today which was a complete shock because I am still spotting. I thought that this was the start to AF but something just told me to take a test. I made a doctors appt for tomorrow but does anyone have insight about the spotting? I thought that if it was implantation bleeding it would be over by now. This is my fourth day of light spotting, mostly brown or pink and just very little red and only when I wipe, none in my underwear. Any insight would be appreciated, this is my first pregnancy.

Thank you!