Is my puppy's diarrhea ever gonna stop?

I've had a boxer puppy now for 3 weeks ( he now is 9 weeks old) Since then he almost constantly has diarrhea.When i went to the vet they had to give him fluids because he was dehydrated. And i know for a fact when i purchased him at the breeder he did not have diarrhea because i went to see him a couple of times before i brought him home and all the puppies where going on a litter box type of thing. I already gave him rice and ground beef for a couple of days and it was better, should i continiue this?? I also have a crate that i put him in over night. He also eats everything he can find on the ground, he already ate my sons pacifier about 5 of them, he pooped them back out though.I don't know i'm kinda at a loss with him. I also have another boxer puppy and they both eat the same food and the other one is fine. Hope someone can help me.