When did the first vomiting occur? If you lift her lip and look at her gums above her teeth, are they the same color as yours, or do they look different? If you touch her gums in this area, are they wet, dry, or sticky? Is she on any chronic medications? Has she had any diarrhea? Can she get up and walk?
There are many reasons why a dog would vomit this much. The most common include gastrointestinal obstruction with a foreign body (such as a sock, or a piece of a toy), intusussception (obstruction of the intestines when they telescope in on themselves), gastric dilatation and volvulus (twisted stomach), toxic ingestion, gastrointestinal infectious disease (viral, bacterial, etc..), kidney disease, liver disease, pancreatitis, or a simple dietary indiscretion. Differentiating these illnesses requires a physical examination by a veterinarian and blood and urine laboratory testing, plus abdominal X-rays.Since your dog has now vomited three times, and she is showing signs of dehydration (the sticky gums), then I think it would be wisest to take her in to the emergency clinic now for an examination.I am attaching a client information handout that I use in my practice that discusses the causes of acute vomiting in dogs in more detail. I hope that you find it useful.Click Here
I hope that this information is of help to you, and I wish you the best of luck with your dog. Please let me know if I can be of further assistance.