Originally Posted by
amsteube
Okay. First of all it is unlikely that the bathroom drained up. The first thing I would do is look at the floor upstairs, mainly around the toilet. Maybe stand on it and kind of push and see if there is any sign of give in the floor. Meaning the the floor was wet and that is where the leak is from. Other than calling a plumber to come and look at it there isn't much you can really do.
The first thing the plumber will want to do if there is a leak is to tear out the floor or ceiling. :(
Have you contacted your insurance company to see if they cover water damage from pipe leaks? They may not but it's worth a shot. After all, that is why you pay for insurance.
Hope this helps,
Aaron