Sorry your dog is so ill.
She must be in a lot of pain if her teeth are rotting to the point of falling out. One of my dogs had severe dental disease (x-breeding puppymill rescue). She would not eat either probably because of how painful her mouth was but as soon as the teeth were removed she started eating. There is also a high risk of blood poisoning with severe dental disease so I'm thinking she needs to visit the vet ASAP. Good Luck