I just had a similar incident with pee-nut and his stool looked like black raspberry jam and he was not eating and vomiting mostly bile. I took him to the vet with a stool sample and he was diagnosed with Hemmorrhagic Gastric Enteritis (HGE) which can be deadly if not treated. The vet said in his condition she would hospitalize him however seeing how attached we were she thought he would be better with me (less stress). So she injected him with fluids which made him look like a yorkie on steroids, and gave him a heavy dose of antibiotics. He was not to eat or drink for 24 hours. And he was put on oral antibiotics for a week, and science diet. By the second day he was back to normal.
I would recommend going to the vet immediately. Good luck