Cat has scabs on back of neck

[Tiffanyann26]

My cat is 9 years old he doesn't go outside he's been an indoor cat since I got him he never had any problems with food  

[opus88]

Usually even though there's never been an issue before it still is often a developt allergy to whatever your feeding, chicken ingredient is common. Can also be a developed insensitivity to an additive or one of the ingredients, I suggest to try changing to a different food that's not chicken, no grains and low carbs such as the gravy or sauce in so many canned diets, if you feed dry switch to cans as there are so many preservatives in dry that can also cause these problems, good luck let us know how it goes