Is my new puppy sick?

I brought home a 2 month old puppy yesterday after meeting him on several occasions. He was very excited and we set up his play pen and let him out around the house. His poop was solid as he went on his mat. Near his scheduled feeding time, we gave him the same food the breeder had been feeding him and he ate it all. After, we gave him a tiny lamb dog treat (we cut a piece as small as a fingernail) and he went crazy over it. He was very friendly and would snuggle up or follow anyone in the house. (There's no small children in the house.) He did not bark at all through the night and the next morning I went to feed him (same time the breeder feeds him) and he growled at me and backed away. After a minute he was ok and I put food in his bowl. I petted him and waited but he did not eat it and went back to sleep. Couple hours later he woke up barking and whining to come out and we took him out and he went diarrhea all over the floor and we cleaned it up. He was energetic all day but we couldn't get him to eat at all, he wouldn't even eat the treat ate yesterday. (He's drinking lots of water though.) Later during the day he started to lose energy and just went to sleep. He kind of looks sad, maybe lonely he left his siblings? We are going to see his condition tomorrow and go to the vet. What do you guys think? I read that this is pretty normal behavior but I also read some things about infections so I'm kind of worried. Thanks.

Hello sorry about what happen to your dog. Don't haven't experience that before, i guess you need to wait for your vet to figure it out why this happening to your dog. And after that post here again about the vet finding. Hope that's not serious and I hope that there's no problem on your pup.
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