Looks like spotting when I wipe and it's been 6 days after I had unprotected sex. Could it be implantation bleeding?

Possibly. It depends on when in your cycle you had intercourse and subsequent spotting. If you had unprotected sex around the middle of your monthly cycle and the spotting is occurring shortly before or around the time you expect your period, it's certainly possible. In that case, I recommend a pregnancy test if your period is also a few days late.