I finally have a medical term for the cause of my bleeding. A subchorionic hematoma.
Without getting too graphic, it's basically a blood clot between my baby's sac and the uterus wall. It will most likely go away on its own, but I am still on bed rest for the rest of this week.
I am happy to announce that some good friends of ours will probably be bringing a baby girl into the world either tonight or tomorrow morning! Despite all my personal worry, it is exciting to hear about others' happy and successful pregnancies. I'm a sucker for a cute baby. =)