If she had a fatty treat before this started or a chew bone or treat of some sort this could be serious as it might be due to pancreatic inflammation which you can read about here
http://www.peteducation.com/article.cfm?cls=2&cat=1580&articleid=335
or a swallowed non food item that can't pass through her system or be vomited up.
If you are seeing any blood in the vomit or anything that looks like coffee grounds (that is often how digested blood looks) then I'd see your vet.
This might be an issue with intestinal parasites such as giardia or coccidia or infection such as campylobacter, listeria, salmonella too.
An over the counter med you might try for digestive upset would be Pepcid or Tagamet or Zantac. Be sure to tell the vet when you see them if you use any of these. You can read about dose amounts (and cautions) scrolling down on the pages here http://www.petplace.com/drug-library/cimetidine-hcl-tagamet/page1.aspx http://www.petplace.com/drug-library/famotidine-pepcid/page1.aspx http://www.petplace.com/drug-library/ranitidine-hcl-zantac/page1.aspx If that helps then you can see if some bland food and plain pedialyte added to the water bowl will help. I would suggest trying boiled chicken meat or hamburger with the fat drained off, mixed with really well cooked rice in a ratio of 1/3 meat to 2/3 rice to see if that works. It's not a balanced diet but OK to use for a few meals while working on controlling digestive upset. But if your vet is not open tomorrow while you can try the above you might want to see if you can be seen later today with her rather than waiting all weekend.
If your dog might have gotten into anything toxic, appears dehydrated (see if a pinch of skin over the shoulder blade stays stuck in a tent form or flows back down normally when released), has a rectal temp over 103.5F (normal is 100.5-102.5 Fahrenheit or 38 - 39.2 Celsius ), has gums or tongue that look white, blue, gray or yellow tinted where they are normally pink, has a slow color refill if you press on a pink area of gum or tongue, is not breathing well, or is becoming lethargic and non responsive to you then you may want to get the dog in to see your vet.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics