My Period Ended, Then 4-5 Days Later I Experienced A

My period ended, then 4-5 days later I experienced a little fluid followed two days later by bleeding and cloying. I took a pregnancy test thinking it could have been a miscarriage but it was negative. Called my doc and she recommended I get my blood taken asap which I did. However, I'm worried and am wondering if you can shine some light on my situation so I can hopefully relax until I meet with my doc tomorrow.. Thank you.