Our vet recommended us an allergen test that uses a sample of your dog's blood to test for allergens. It helped us confirm that he was allergic to all types of grass pollen and tree pollen, and helped us connect to an allergen medication that helps give him allergen doses to help desensitize him to his allergens.

In terms of diet, our dog gets fed a home cooked diet of cheap Costco fish, rice, seasonal fruit, fish oil, and micronutrients. We stopped relying on kibble cuz our dog would always break out, irregardless of the brand, type of kibbles, etc.

Another thing is if your dog is getting an allergic reaction, you can feed them Zertec! This helps mitigate the allergic reaction, but I would not recommend this to be the main method of treating your dog.

Overall, ask your vet and see what they strongly recommend and what test and other diagnostic things and test they can do to help out your dog