i had the same thing happen to me they gave me a gel to insert at night for 5 days and i havent seen green/ yellow discharge ever since.
What I've noticed is on an off I've had this even some clearish/very light brownish d/c but always turns out to be nothing. My on says you vag just makes extra secretions when pregnant sometimes. But if it starts smelling or turns bright bright green or red call an see your ob. We're not far enough to feel our babies move yet so better be safe than sorry of not knowinf
I think you should call your obgyn..better safe than sorry.