We got our puppy about one month ago, and he's a really great dog, really smart and well behaved. But he's had diarrhea since before we got him from the rescue. He's been wormed, the vet gave him some paste that was supposed to make it stop. Then the vet gave him 2 rounds of Flagyl that didn't work, and now he's taking something called Proviable that started to work, and now its not. He's gaining weight like normal, and he has all the energy that a 5 month old puppy should have. What could be causing this, and why doesn't my vet give me any ideas as to why he has this problem? He's had it for a month now!