We have a 5 month old male Bernese puppy. We switched him to adult food almost a month ago and he was doing great the first two weeks (we went from Fromm Large Breed puppy to Fromm Large Breed Adult food). Then he started having diarrhea about 10 days ago. This lasted about 2-3 days and as soon as we fed him rice and chicken or beef, he was good for about a week, even when transitioned back to his normal food. Then this morning he pooped once (this was all before he ate breakfast) and then had a looser stool. Then he threw up some bile and he has never thrown up before. He was fine all day. This evening, we took him for a walk, but it was a little warmer and humid. He did fine walking and he ate rice and boiled chicken about an hour after walking. Within 30 minutes he had thrown everything up and has since been very calm. 10 days ago, he also had a little bit of yellow discharge from his eyes and he usually has this, but it's white. This hasn't been the case for about a week. Any suggestions? We haven't gone to the vet yet. We aren't sure if it is something he ate when walking because we take him in the woods a lot to walk or if it's his food. Or maybe it was too warm for him today and he got a little heat stroke (it was in the low 70's and we were in the shade most of the time, but humid). We will definitely be taking him to the vet if he's still bad the next day or two. Thanks for any help!

The health of our puppy isn't easy. I advise you to see a vet if he doesn't get better in a few days.
Do you have change the food at once ? Because he has always been accustomed to eating only one food so his stomach doesn't get used.
I think that you must resume the old food and you mix it with the new.
In addition, the Bernese mountain dogs actually hate the heat and can't bear it.
Good luck and we wait news of your puppy

__________________
Love bernese moutains