should I take a pregnancy test?

As embarrassed as I am to admit, I had unprotected sex with a stranger about 2.5 weeks ago. I started my 'period' two days ago, but it's been the lightest it's ever been. The first day and a half there was blood, now it's mostly pinkish spotting which is completely abnormal for me. I've also been overly tired, sleeping 8 hours at night + a 2 hour nap, accompanied by headaches all day for the past week.