Does your boy eat non food items like Rawhides, bones or greenies?
Does he have diarrhea?
Is he drinking water and able to hold it down?
What was the last thing he ate beore this started?
You need to give your vet a call regarding your boy as the symptoms he is showing indicates an obstruction of the GI tract. This can be confirmed with X-rays and the obstruction will have to be removed. Unfortunately there is not a home remedy for this. In the future, consider bully sticks and stuffed kong toys for him instead of bones and/or rawhide bones. Please have him seen asap. Good luck and do let me know how you make out with him.