Thanks for the question
While I cannot diagnose this over the internet I can tell you the following :
1. As far as the colorless and odorless discharge is concerned
this could be urinary incontinence of the spayed bitch. While this is in fact urine many clients have told me in the past that in this case it is colorless and odorless. I will tell you more about this condition :
A. As its name suggests it affects spayed bitches.
B. The dog is not aware she is doing it, you will see bed wetting, damp patches on the carpet where the dog has been lying, and urine will dribble out of the dog as she walks. These dogs often lick their vulva area which will be wet.
C. The cause of this disease is relaxation of the urethral sphincter.
D. It can be treated via prescription drugs your vet can supply, one group of drugs used to treat this condition contain phenylpropanolamine, the one I use had the trade name Propalin or Proin. However there are other drugs which can be used such as female hormones.
2. As far as the diarrhoea is concerned
the white rice is a good idea, your vet may also suggest something like the following :
A. Starve her for 24 hours but make sure she has access to water.
B. The next day feed her four or five small light meals in the day. These meals should be the likes of chicken
, fish, scrambled egg etc. with a little rice.
C. If she pick up on this diet gradually reintroduce her normal diet over the next few days.
Live yogurt added to the food can often help. Some gastro-enteritis situations are caused by an imbalance in the bacteria in your dog's gut. Live yogurt is full of " good " bacteria and will seed them into your dog's intestinal tract and restore the balance.
As there are possibly two conditions going on here your idea of seeing the vet tomorrow seems a good idea. Usually neither of these conditions will be too serious but it could be that prescription drugs will sort things out quicker. Good luck with your dog ...
If I have not covered your question fully enough or you would like to ask more I will be online for the next hour or so and I will be at your disposal.Scott Nimmo BVMS MRCVS