Diarrhea can cause a young pup to dehydrate. If you have not seen any improvement then call the vet. Did they get a stool sample and look at it under the microscope? Sometimes if the stool is entirely runny it is difficult to get an accurate look at the sample to determine the cause. You may need to get another one to the vet to be checked. It is hard to treat something without a proper diagnosis.
As far as her activity....she is a Yorkie!
I have to tell you that I was unsure if I had a possessed puppy when Gracie was a young! I had never had a terrier before. I had trained plenty of other breeds of dogs but terriers are different. I would suggest you get a good Yorkie book and read up on the breed. These cute little angels were bred to kill rodents. They are feisty and full of energy. If you learn how to work with that temperament and not against it you will be less frustrated.
My little girl's idea of a good time is to have a good fight with her toys or a game of chase with me. Lots of exercise, play, and training is about your only defense. A tired puppy is a well behaved puppy.
