What you need to do, without any fuss, put the food bowl down, if the puppy doesn't eat after 15 minutes, no fuss, no begging to eat, just pick it up. This is the important part, as hard as it might be for you, NO FOOD or TREATS until the next meal time, but always do keep water available. Repeat. Within a few days, your puppy will should be eating regularly."
Good advise! My DW got a puppy that had the same problem. I told her to stop feeding treats, and take up the food. He would eat in a few days. She of course would not listen to me. "O NO I am not killing the dog" she would reply. Off to the vet blood work, and exam about $300.00 and told to stop the treats and take away the food then he would eat in a few days. The advise from her vet worked.
Chuck, Cooper and Nina
Shelter dogs aren't broken. They've simply experienced more life than other dogs. If they were human, we would call them wise. They would be the ones with tales to tell and stories to write. Do not pity a shelter dog. Adopt one.