hmm do your dog have the problem of eating too fast? 
mine used to wolf down her food and would vomit like 5mins after eating.. 
i did some research and found this bowl designed to slow down dogs' eating time which really helped her slow down and the vomiting stopped.  
check it out at www.dapperpetstore.com. i also bought the dog bowl which prevents mistys mouth from getting all wet and brown from water stains. 
hope this helps! 
bludog