If he ate ice-cream as you mentioned in the repeat of this question that might be the problem.
Sometimes the fat content will bother a dog and you can read about that here
http://www.peteducation.com/article.cfm?c=2+1580&aid=335
Sometimes the dairy will upset the dog's stomach as many dogs become intolerant of dairy products once they are weaned.
An over the counter med you might try to soothe an irritated intestinal tract would be Pepcid or Tagamet or Zantac.
Be sure to tell the vet when you see them if you use any of these.
You can read about dose amounts (and cautions) scrolling down on the pages here
http://www.petplace.com/drug-library/cimetidine-hcl-tagamet/page1.aspx
http://www.petplace.com/drug-library/famotidine-pepcid/page1.aspx
http://www.petplace.com/drug-library/ranitidine-hcl-zantac/page1.aspx
But if that doesn't help then you may want to see your vet for in person care.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics