From what you are describing, Buddy is quite sick. The most common causes of vomiting are pancreatitis (inflammation of the pancreatitis secondary to high fat intake), gastroenteritis (inflammation of the gastrointestinal tract secondary to ingestion of an irritant), ingestion of a foreign object, infection (usually in the kidneys or liver) and organ dysfunction (liver or kidney disease). Since you are describing Buddy as inactive and not able to keep water down, I am worried that he may be quite dehydrated. Sometimes nausea will subside over the course of a day or two, but Buddy sounds like he should not wait to see a veterinarian.
I need to ask a few questions to better understand what is going on with him.
When did he start vomiting?
Is he trying to eat any food?
Is there anything that he could have ingested (foreign material, meats, cheeses, etc)?
Does he have any history of other medical issues?
Is he on any medications? Thank you