If she was given a pain med this may be the reason for her gastric bleeding. Some dogs react to meds such as that with ulcers.
If you cannot see a vet with her tonight then you might consider trying an over the counter med such as Pepcid or Tagamet or Zantac which are used for treating bleeding ulcers.
Be sure to tell the vet when you see them if you use any of these. Bring the package if you need to for help with translation issues.
You can read about dose amounts for these meds (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 she 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, or is becoming lethargic and non responsive to you then I'd suggest trying to find help to get you emergency vet care.
Hope this helps you!

You said she vomited red. That red color is probably from blood. Bleeding ulcers are one thing that can cause a dog to vomit blood.
Irritation from pain meds can cause irritation and bleeding of the intestinal tract.
She might also have a cut along the area the tube was put down her throat for anesthesia which could be bleeding.
If her stomach or throat hurts or she feels nauseous she won't want to drink or eat.