I had my first ultrasound today. I am 5w 2d. They saw the gestational sac like they wanted. But next to the sac was some fluid, the doc couldn't tell if it was blood or fluid. He didn't seem concerned, he told me I might spot, I could bleed heavily, or nothing will happen at all. He said it could be a blood clot. I go back next week for another sono. Has anyone experienced this before? What happened?