Spotting, and now I'm worried.

Hey ladies, I'm a little over 6 weeks and I just started spotting. It's not very heavy and it's brown but I am cramping a little bit with it. Nothing to severe but this is my 1st pregnancy and I'm so scared and nervous and I've got myself worried now! I called my doc. and she said that it's still to early to see anything on an ultrasound. I'm scheduled for my first ultrasound on Tuesday (5 days away) and I'm a nervous wreck. Is this normal or should I be expecting the worst?