Your child may be in danger.
Dark brown vomiting
in empty stomach may be due to hemorrhage (bleeding) in gastrointestinal(GI) tract. Blood turns brown after clotting and reacting with GI acid and enzymes in stomach.
Even though the blood reports are normal (I don't know what reports you have done), refusal to eat / drink with fever is danger sign. It could be due to septicemia
Fever of 104.7 degree F is itself suggestive of underlying severe disease.
If your child is not taking food / water, he will be dehydrated soon and may need intravenous fluid therapy
Other possibility of the dark brown colour could be due to any residue of oral medications that the child had.
Common causes of these symptoms are septicemia, malaria, typhoid fever
etc. All of these needs urgent treatment. So, it would be wise to get your child examined by doctor as soon as possible and start necessary treatment. The condition of your child is serious.