Thanks for the additional information. I really appreciate it.
Unfortunately to me, this sounds a great deal like Parvo.
Parvovirus is an incredibly contagious, usually fatal intestinal disease that dogs get who haven't been vaccinated thoroughly for the illness. Some dog breeds, such as Rottweilers and Pitbulls tend to be more susceptible to getting the illness than other breeds, however, any breed can get it.
Unfortunately when the symptoms of Parvo appear, the dog has already been infected with the illness for a while, and the fact that she hasn't been eating for several days and has been doing vomiting and diarrhea, it makes me very concerned that she could be in very critical condition.
The best chance at survival your friends dog has now is to be in a veterinary clinic, receiving intensive care. She needs IV fluids, antibiotics, medications to stop the diarrhea and eventual vomiting. Parvo is not an illness that can be successfully treated at home.
I understand that it's Tuesday evening and the average clinic is either closed or almost closed, but the best chance this dog has for survival is to have her seen by an emergency vet as soon as possible. If you're not sure where an emergency vet is in your area, you can go to: http://www.vetlocator.com and plug in your zip code. They'll point your friend in the direction of the one nearest to you.
I'll keep my fingers crossed for him.