Implantation Bleeding Implantation Bleeding?

Implantation Bleeding? - implantation bleeding

Recently I had the pills. My husband and I decided to be cautious, but he went out the window ...... unprotected sex, we had to start for several days after I was about my new pack of pills. Approximately two weeks later, my stomach started cramping and I had pink / brown when dried blood. I thought I would start my period, but stopped. Was it implantation bleeding or periods only bone of the pill? When can I take a pregnancy test?