I would consult a vet. Your dog might have a medical issue or a dental problem. I had a dog with a stomach ulcer several years who could not eat kibble; it was too processed for him and apparently upset his stomach. We tried a number of kibbles then realized there was something more to it…every time he would excitedly eat the new kibble for a few days then stop eating it. He was always willing to try something new…but it still made him feel bad. đ We ended up putting him on an acid reducer to help with his ulcer and I home cooked as he felt better but still could not eat the kibble consistently. If I had to do it again I would have tried a raw diet for him. I’d consult a vet to confirm whether there is anything physically wrong, then consider trying a raw diet (the prepared mixes are expensive but more convenient than making your own). Kibble might be too processed for him.
