Welcome to JustAnswer. I'm a licensed veterinarian and I'll be happy to help. I am so sorry to hear about Stubby! So many things can cause vomiting. . .from a foreign body, to pancreatitis, to cancer (less likely in a young cat). Stubby needs to be adequately diagnosed as to the cause and not just treated for the symptom of vomiting.
Hepatic lipidosis is caused in cats who don't eat for several days, and it in itself can/will be fatal. The treatment for this is to control the nausea it alone causes and get food into him.
In Stubby's case he now has two serious problems, the unknown initial cause of his nausea and lack of appetite and now the hepatic lipidosis from not eating.
There really isn't any treatment for him at home since Cerenia isn't controlling his nausea and vomiting, and just waiting for him to start eating is going to make him worse. My educated guess is that he won't start eating without further diagnostics, support and treatment in hospital.
Stubby needs aggressive diagnostics, support and treatment, or I'm afraid you will lose him. . .I am so sorry! Has your vet checked him with an x ray or ultasound of his abdomen? Has he checked his blood for pancreatitis along with liver and kidney
function? If these have been done without any concrete diagnosis, then we need to look further. I think my computer or the web site is having trouble and I had to resend my answer. I hope at least one gets to you. I also did offer a phone call if you'd like.