brown spotting

I have been spotting brown for a week now.  Last Sunday when it started I went to ER (under the advice of my OB) they did an ultrasound and saw heartbeat.  Cervix was closed, everything looked ok.  I then followed up with my OB on Wednesday and the same thing.  Heartbeat good and closed cervix.  The spotting has gotten lighter every day and then yesterday it was gone.  Today woke up and it's back and this time dark again. (Still brown, no red). I have an appt this Wednesday to see my OB again, but I just cant stop worrying!!  Does anyone have any advice or similar experiences??  I'm 9 weeks 3 days.  Thanks .