Spotting does seem to be very common until week 10. If I was you I would try to distract myself as the more aware you are the more anxious you'll be and that won't help. Keep your mind busy, do puzzles, listen to music, try a new recipe, have a long warm bath, whatever it is that works for you that takes your mind away for a few minutes/hours(hopefully) and isn't too exerting.
In a week hopefully your ultrasound will give you a clearer picture of what is going on and will alleviate your worries. Remember if your doctor doesn't seem too concerned, although its worrying for you, its probably because they see it all the time and its quite common. I'll be thinking of you ((hugs)) to you.
I had lots of spotting early on, too, and it lasted for a bit more than a month. I didn't want to get too attached to being pregnant because I felt that any day I could miscarry. My spotting was almost exclusively brown and not heavy, though. I did not miscarry, and the spotting went away sometime around week 9-10.
My understanding is that if you have bright red spotting with clots and cramping, then you should be worried. Brown spotting - especially if not heavy - is usually OK.
I was spotting on and off from week 4 till all the week to week 10 and it was due to a subchoronic hematoma. I was given progresterone supplements and told to take it easy and let the spotting go off on its own. At week 10 the spotting stopped once and for all and the scan showed the hematoma had disappeared (thank God!) so just take it easy and its good she is sending you for an ultraound to keep an eye on the spotting. So take it easy and don carry anything heavy and wait till your scan next week to see if your Ob can see any hematoma and if so, has it disappeared.