I'm not able to help with the vomiting, the experts will be along soon. But I switched Herman from Eukanuba Pure Puppy to Earthborn. I was always cautious with the Eukanuba because I noticed some stores had older expiration dates than others - this particular line from Eukanuba was very hard to find. So it's possible its the food - or the treat ball. They could be allergic to something in that as well - they have one version that has wheat/soy/corn and they also have a wheat/soy/corn free version.