Take your dog to a vet or emergency clinic immediately. Could be a throat obstruction or something equally serious. If you care about your dog, you should make sure he/she gets medical attention as soon as possible.
I would take him to the vet to have them check him out and make sure that he is going to be ok. It might be something serious and it might not be. It is better safe than sorry in a case like this. I hope this helps you out.