Bleeding at 7 weeks

Last night I started bleeding. It wasn't much, and it was light red/pink. I went to the er right away. They did an ultrasound and vaginal sonogram and the baby was there, and was fine. The heartbeat was 124. The doctor said that everything was normal other than the bleeding. They sent me home, and said to relax and not worry. Which is really difficult. This morning there was very little brown blood on and off. I am feeling good and a little nauseous, but I feel like something is gong to happen. Is it normal to bleed and everything be fine?