This could be from stress. You can see if a bland diet and some plain pedialyte will help her stomach calm down.
For a bland diet you can use baby food meats (make sure no onion in them) or you can boil some chicken meat or hamberger with a little salt and drain off the fat then mix the remaining broth and meat with plain cooked white rice for her meals.
Use the pedialyte instead of water to help keep her hydrated.
You can add some plain canned pumpkin or some cooked sweet potato to the rice to help by adding fiber which aids in controling diarrhea.
If she gets worse head for the emergency vet.
If she gets better slowly wean her back on dog food and have the vet check a stool sample for intestinal parasites such as coccidia or giardia or worms.
Hope this helps you!

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