Brown Discharge in Early Pregnancy: What Could It Mean?

Question
Here's my history:

July 2003: m/c at 5.5 weeks (started with brown discharge)

October 2003: missed m/c at 7.5 weeks (D&C)

March 2004: was pregnant, and had lots of bleeding from a subchorionic hemorrhage(gave birth to a healthy boy in November)

I'm pregnant again. 5.5 weeks. Now I'm having dark brown discharge. Started last night. It's very sludgy. It's not gushing, but it's constantly there. More than just a tiny bit on toilet paper.

Four days ago my HCG was 6,000 (up from 610 five days before) and progesterone was 16.5 (up from 8 5 days before).

Am I doomed? Seems too late for implantation bleeding and too early for a subchorionic hemorrhage. I didn't have intercourse or have an exam. Could it be from lifting my heavy 10-month-old?  

Answer
It is common to have some brown discharge at 5.5 weeks gestatin. It is a bit too early for a sonogram to show a fetus. After 6 weeks (from the first day of your last period) a sonogram will show a fetus and a fetal heartbeat. I would recommend that you get a sonogram at that time, if you still have spotting. Often, a brown discharge is merely "old blood" being pushed from the uterus by the growing fetus. Your HCG and progesterone appear to be within normal limits. Implantation bleeding occurs 8 days after conception. You are past that time.