I would go to the doc. I too had bleeding this time round (5 1/2wks), only spotting but i freaked (i'd been walking round and carrying my DD) Doc says it was prob just a little blood from when the placenta attached but to be safe, rest for a week and go back and have another u/s again a week later as they couldnt detect it at 5 1/2.
But still i would get it checked, better to be safe, good luck, hope all is well.