This is the point I would take my dog to the vet. Although I don’t know your dog’s eating habits
He refuses food for several days, then binge eats for a day. Will not repeat the same foods for meals. Seems to have been born with the forbidden knowledge that food can be different every meal. At 10 weeks old the first vet told us to not give in and he would eventually eat. A week later we called back and informed the vet that his food had been sitting on the table untouched for the whole 7 days. That resulted in an immediate follow-up visit where the testing started.
One and a half years later, his team of top nation wide vet specialists have run dozens of tests and don’t have an answer. He does make for good Lemmy OC content though :D
Prognosis: picki boi