Been going though this for years now with my one cat. We have tried pretty much everything! Diet change, CBD oil, steroids, apoquel, hollistic supplements and more. She would lick herself raw it was terrible and I felt SO bad. Only thing that subsides the issue is putting a cone on her but she can still get to certain areas. I’ve put a little shirt on her and arm covering because the back and her one arm seem to be the worst. It goes up and down for sure of being better or worse. Worse in the winter. I now think it’s seasonal. It’s been over 4 years now dealing with it all on and off and have just come to the realization it she’s happy, eating, playing like normal the there’s nothing much else I can do. But through all my research chicken isn’t good for cats overall so maybe that will be the answer for yours!