Exactly what she said! Its just your body adjusting to being pregnant and your uterus getting ready for all the fun stuff tarts about to take place.
If you end up bleeding heavy such as clots go to the hospital other than that don't worry. Congratulations!
sounds healthy for 5 (almost 6) weeks.
implantation doesn't occur until about week 4 which can cause light pink spotting.
brown blood is old blood, so this can be from the implantation that occurred last week, or from the ultrasound (assuming it was an internal ultrasound) that can cause bleeding as well.
that early on for an ultrasound isn't going to show much as the embryo is barely larger than a poppy seed, and its heart is just stating to beat.
The vomiting is a very good sign. try ad eat when you can, snack on flavorless things like soda crackers and water. dont forget your prenatal vitamins.