Period during pregnancy?

Is it possible? And still continue with a healthy pregnancy? 
I started spotting brown last week which turned red 3 days ago. Now its more of a period with cramps. Im currently suppose to be 8 weeks. 
There are a few passingbof blood clots no larger than a cm but there is more than a usual period. When i had my first ultrasound 2 days ago, there wasnt anything visible so continued for lab test which my first hcg levels were 7650 or do. Now currently waiting to do my second one tomorrow. Beyond scared?