I'm wondering if it HGE? That is hemhorrhagic gastroenteritis and it's characterized by blood in the vomit, but more often in the stool. This is gross, but the blood in the stool is often described as having a strawberry jam-like appearance. Anyway, one of my pugs had it. It can be very dangerous and life-threatening if untreated. The dog can basically bleed to death -- veins collapse, etc. However, with treatment most dogs are just fine. My dog was admitted to the vet for 2 days for IV fluids and IV antibiotics. She has been fine since and that was about 2 years ago. I always carefully examine her poo -- I'm the poo police as my husband says -- because I'm always so afraid of it happening again.
Hope your dog is o.k. Sounds like you're doing the right thing and she should be fine. I know that it's scary though to see all of that red blood!! Good luck.