Spotting for 4 days and positive pregnancy test

Hello everyone, I am currently waiting to go to the Dr. I have been spotting for 4 days now and I took a pregnancy test and it was positive... My math doesn't add up because my last period ended on December 23. pregnancy test positive on December 30... Is it possible ?? Or was I pregnant before and what I thought it was my period was actually a miscarriage? I will have these questions answered Monday when I go to the Dr but I just can't deal with the waiting... Did someone went through the same?