Thank you everyone for your own stories and suggestions. After driving back and fourth and chatting at a few different places for three hours

I’ve leaned more on that it is likely a protein allergy to chicken. I have decided to go with Now Fresh, grain free large breed puppy. The hardest part was trying to find large breed puppy food that didn’t have chicken in it. So this one the protein is Turkey, duck and salmon, and just happens to be grain free. It is super expensive… but if it works I’ll be so happy! Also got a better pre probiotic than what we had, it has slippery elm in it and is supposed to help the stomach lining/inflammation, and sooth the tummy. Really hope in a few days he’s feeling better!