Brown discharge (like old blood) @ 28 1/2 weeks?

 Hi everyone.

Earlier today when I went to the bathroom there was brown discharge (like old blood, sort of how it used to be right before my period started.) it wasn't so much that it was getting on my underwear, and wasn't super-slimy (so I don't think it was my mucus plug, plus it's pretty early for that.)

Any ideas? Have you had this happen?

Have you had intercourse lately? That can happen from having sex!

The doctor ended up having me come in yesterday (I would have gone on Saturday, probably, but there was a debacle with the rude lady at the answering service - she never gave him the message). I had a full workup (HR check, ultrasound, blood, urine, cervical exam) and everything is perfect, so no worries.

There are a couple of things that happened in the few days prior that might have dislodged some old uterine lining. I've been told that I have to reduce my field work and don't go to sites that are slippery, unstable, or too far away from medical help should I need it (I'm a marine biologist.)