Do you think he could've eaten something? A plant or anything? I'm not sure what to give him to settle his tummy. If he continues throwing up he should see a vet. They can get dehydrated pretty easily. Poor Buster..I know you must be worried about him..unfortunately puppies eat everything! Does he feel warm? How do his eyes look? I wish I could help...hopefully someone will know more..and hopefully he just ate too much grass and it's over!