Possibly Implantation Bleeding

Two days ago, directly after sex, I started getting period like cramps, and I started spotting, and now am barely spotting with no cramps. my period isn't due for 9-10 days, my husband and I had sex twice during my ovulation period, which was about 6-8 days prior to my spotting. I haven't really had any of my normal period symptoms. I am not on any birth control and we only use the withdrawl method.