I am sorry for the late response to your question. Vomiting , diarrhea, loss of appetite and lethargy are symptoms that needed immediate medical attention. Vomiting with diarrhea may be a sign of infection, intestinal disease and intestinal blockage. Intestinal parasites such as roundworm and giardia can infect your dog and causes these symptoms. Bacterial infection like salmonella and campylobactor can likewise have the same signs. Diseases such pancreatitis, distemper, coronavirus and parvovirus can cause vomiting and diarrhea. Ingestion of foreign objects can block the intestinal tract can also produce vomiting and diarrhea. It is therefore important for a physical and laboratory examination of your dog to determine the cause of the vomiting and diarrhea so that the right treatment and medication can be carried put to your dog. Take care.