We have had our mastiff puppy to vet he said the check went well and couldn't find anything.. But he still won't eat and is vomiting and still has the runs I am at my wits end he is losing wieght and it is scaring me to death I have even tried human food and still nothing.Is there any one out there that can help me.

Try another vet.

No good vet will send a puppy away who is vomiting and has diarrhea without finding out what is wrong.

How long have you had him for and how long has this been going on?