Implantation Bleeding early ?

Okay, so my period ended 3 days ago on Wednesday and I had unprotected sex the next day Thursday. It's now Saturday and I was in the middle of washing and saw a spot of blood after washing my vaginal area. I got out the shower and dried off and when I dried my vaginal area there was no blood. I did research on implantation bleedin and that occurs around the 22-25 of your menstruation cycle. However, I'm only on day 8. Can someone please give me advice on what could be happening ?