Been through this with one of my foster dog who would not eat, he also had runny poops and he was tired all the time. We took him to the vet and he spent the night there. He was diagnosed with stress colitis. I bought super smelly chicken baby food without garlic and mixed it with his dog food, he started eating. It was too the point were he refused even raw food...it was more stressful for me because i was worried about him constantly.