Spotting like that often occurs in the implantation process. There is nothing the doctors can do at this time, so the best recommendation is to get a box of home pregnancy tests...get a value pack with more than 1. Experience tells me that no matter what they claim to do, most won't show a positive until after a missed period, sometimes over a week or 2 later.
Miscarriages can start out as spotting like that, but usually end up being quick, heavy and clotty.
Many 1st pregnancies end of miscarrying...It;s the body's "trial run".
If it ends up being a period or you get one in the next week or so, relax!
When I was trying to get pregnant, I convinced myself that everything was a sign that I was pregnant. The mind works in mysterious ways.
When you stop focusing on getting pregnant...You will! Trust me!
Best of luck! and remember...Relax, it works!