I am sorry for the late response to your question. From the information that you stated and the picture, this could be due to allergies and ingestion of toxic substance. It could also be due to bacterial or viral infection. Because of the vomiting and diarrhea, dehydration is the primary concern that must be address immediately. Check the skin on the neck by pinching and pulling. If it lost its elasticity and it takes a couple of seconds or more to return to normal then your dog is dehydrated. Another way of checking for dehydration is through your dog's gum. If its pale,dry and sticky , then your dog is dehydrated. If your dog is dehydrated, take him to the emergency clinic as soon as possible. If not try giving him ice cubes for him to lick. Offer him chicken or beef stock. give unflavored pedialyte mix in water in a 50-50 mix. If he's still not drinking use a large syringe and give your dog 1/4 cup of pedialyte every 20-30 minutes for 8 hours. Bring him to the vet as soon as possible. Take care and good luck.