HI LG, not sure if this will help or not but ill tell you what happened to me last week when I was 12 weeks... I woke up, and when I went to the toilet noticed the smallest amount of brown blood. Went for my first trimester screen the next day and it was all ok. Turned out I had a bleed in/on the placenta which is pretty common. The ultrasound lady (not sure what they are called) described it is 'abnormally normal' and it didn't worry her. Not sure if that will help you, but thats my experience!

I am sure you will be fine, call the ob's clinic if your stressed though. XXX
Take it easy!