Thanks, Ginger, for bumping this post. I didn't see it at all until tonight.
I would definitely take a stool sample to the vet's office and have him run a fecal for you. Watery stools like this out of the blue can be caused by any number of things.
Have you changed foods suddenly? Is there a possibility that she could have eaten something that you don't know about (ie, could a child have fed her something or could she have been counter surfing or garbage picking)? Has she been around any strange dogs lately?
The only way to tell if there is a parasite (bacteria, worms, any type of organism) in the stool is to check it under a microscope. It's a simple test and you wouldn't even have to take the dog to the vet to have it done. You could just take a sample of the stool and have them do the fecal first, and then depending upon the results of the test, THEN you could make an appointment to take her in if further examination is necessary.
I would do that first thing in the morning. You don't even necessarily have to call first, just collect the stool and go to the vet's with it. Explain what has been going on and ask if they will check it for you, and just take it from there.
Please post back and let us know what transpires.
Ghilly
So sorry you didn't get an answer before. I am not sure what this is, but at least my posting a reply will push this up the list...! Then hopefully someone else might have some help to give you.
There could be lots of reasons for this. The most obvious is, has she had any unusual or rich food lately, or table scraps which may not suit her? Or has she sneaked something out of a trash bin? Is she eating/drinking as normal? If she felt bad, you would probably know, because she would likely refuse food. However, it might be best not to just try and suppress this diarrhoea, but to find out the cause of it, and take her to be checked out at the vet. I know this sounds yucky...but I would take a stool sample with you, if you can catch one! It might help if they need to run tests for anything.