Q. He is not eating or drinking seems like he has no energy and vomiting and seems like he weak
DR. CHRISTIE LONG, D.V.M., C.V.A.
A. Causes of not eating and vomiting can be many. Gastrointestinal infection, caused by bacteria (salmonella, for example) or viruses or parasites (although parasite infections tend to be more mild, but giardia can make them feel pretty bad) can be a cause. Eating something he shouldn't have, like the trash or rotten food can cause it. Intestinal obstruction can cause vomiting as well. Other causes (non-GI) of vomiting include kidney failure (can be due to many things, such as toxins, kidney stones, cancer) or liver diseases or liver failure.
The vomiting is concerning, however the weakness and lack of energy implies that he's either seriously dehydrated or there's a lot more going on than just s simple case of vomiting. He needs to see a vet and have testing, likely to include x-rays and/or blood work, to see what's going on, so that it can be treated.
LINDSEY EDWARDS MVB, BSC, IVCA
A. Your dog is definitely unwell and should be assessed and treated as soon as possible. He may be dehydrated and running a fever