Dog Vomiting Yellow Foamy Liquid

Dog Vomiting Yellow Foamy Liquid

i dont know what my dog has ?

Yesterday I saw that my dog was throwing up a foamy yellow liquid. Then call the doctor and she told me that it could be heartburn or that he could have stress (fear of something). And then she told me that if he continued vomiting, it might be gastritis. WHAT IS IT?????????????
H E L P !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SOS

l am only a vet nurse but i your dog has been eating grass and throws up a couple of times it means it has an upset tummy.If it is doing it all the time take it to emergency or your vet as no one in this case can give you an answer over the phone.Dogs do get gastro like humans and normally have diarrhea and some vomiting usually the very loose poos take no chances as l do not know if your pet is inoculated against parbo and distemper if yes you can rule that out