I've been having periods for 17 years but this is a new one for me. Apologies in advance for the details.
I just got up to go to the loo, and as I walked into the bathroom, what looked like brown water fell out of me and splashed over the bathroom floor. 
It was not thick like period blood or normal discharge. It was literally like water, but a strange brown, lighter brown than the post-period brown discharge I get. Definitely from vagina. I felt it 'falling' out. What in the world is this?!
I also went to the loo at 3am, so must have appeared since then. I'm not pregnant, period due next week.