Has she lost her appetite as well?
How long has she been vomiting?
Does she eat any non food items such as rawhides, greenies, bone, grass etc.?
Do she eat any human food ? If so what?
Could she have gotten into any garbage?
Thank you for that information. Fatty human food can cause pancreatitis so if she has eaten anything fatty such as steak, ham, pork gravy, etc. then this can cause a problem. I will direct you to a site that will tell you symptoms and what the treatments are.
Grass or other non food items can cause a blockage of the intestines. A blockage would not allow food and water to pass so it is brought back up as soon as the dog eats or drinks. Is she has no appetite as well, along with a change in stool and lethargy you will want to bring her in as an obstruction would require surgery.
Dogs do get viruses now and then and these usually resolve on their own within 12 hours. You can try feeding her a bland diet of boiled chicken and cooked white rice and see how she does with that. If she refuses it or vomits it up, then she should be seen.
Give only small amounts of water so she can't take in so much at once. This may mean filling the bowl a little more often but it is important to keep her hydrated.
Since we are in a weekend, if symptoms worsen try to get her to your vet today to avoid an expensive after hours bill from an ER vet.