Orijen is too rich for some dogs. I'd give it another couple days, and if he's not handling it any better I'd switch to something different. It is a good quality kibble, just doesn't work for some dogs and gives them runny poop.
My dogs are so used to getting their food switched that I can just switch to the new food right away without issues. Again, doesn't work for every dog and puppies can be especially sensitive to new foods.
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