Has anyone had dark red blood during Early Pregnancy?

Yesterday I had light brown spotting with mild cramps and today I woke up to dark red blood(doesn't fill up a pad) with the same mild cramps. I have an appt today & wanted to see if anyone else is experiencing the same.. sn: I had a U/S Friday and the doctor didn't see a sac.... She said it could be too early. My HCG levels were 454 Friday & today I'll find out what they were for yesterday....... Will keep you guys updated.... Could this be a ectopic?