Have you checked to see if he has a skin tent? Has he passed faeces ok? Is he drinking a lot of water then vomiting or is it even with small amounts? If he were mine, I would give him until the morning then if no better get him to the vet, esp if there is the risk of a foreign body. Just give him small amounts of water little and often tonight. It might even be worth ringing the on call vet for their advice.