Spotting, could I be pregnant?

Kristin
So I was supposed to get my period on Wednesday, it hasn't shown up yet.  I have been spotting since Tuesday (4 days now) and got a negative when I tested on Wednesday.  Spotting is unusual for me so this is very weird.  I haven't been feeling any pregnancy or pms symptoms.
Did any of you experience something like this in the early days of pregnancy?