Implantation or Rough Sex? TMI!

Hi, girls. I’ve been having frequent sex with my boyfriend, and we have been using the withdrawal method. However, we had really rough sex today. I didn’t notice bleeding right after sex, but I didn’t exactly check. Anyway, I found this in my underwear. Can any of you help me as to whether it is just a side effect of rough sex (I’ve bled in the past from it) or if it’s implantation? Thank you girls!