Hello and welcome. We have a free advise section that may take time to receive a response and a paid one through which your response should reach you in about an hour or at times even earlier. The symptoms can be related to various gastric conditions and even vertigo. Instead of finding food which he can keep down, which in my opinion is going to be difficult as long as the source of his trouble is present let us move forward towards a diagnosis and solve the issue permanently. I recommend an upper GI endoscopy to help visualize his inside and rule out/confirm conditions like ulcers, etc. For now make sure you give him plenty of fluids, restrict him from smoking or consuming alcohol, avoid fried/fatty/oily and spicy food, avoid carbonated drinks, and avoid stress. Please visit a doctor for the endoscopy and a few blood tests. You can also initiate any over the counter antacids for now like omeprazole, pantoprazole or even ranitidine. Best wishes.