If he is vomiting that much, and he can't keep any food down, then he needs to see a vet right away! There are so many different things, that are causing him to vomit and not be able to hold down any food, one of them being Parvo, which can be deadly if not caught and treatedd on time, that in all reality, the only one who can determine what the problem is and treat it properly, is a veterinarian! This is really a situation you should not put off!!! Hope your poor little guy is ok!