How can you tell if your dog is sick...without a very expensive vet trip?

Is he neutered? Intact male dogs may act in this way if a female in heat is close by and he is pining for her. The throwing up would be a red flag, and could possibly mean it is something else. The fact that he isn't eating or drinking means he is getting dehydrated, he could die from that. I would suggest you take him to a vet for treatment, or you could lose him.