My cat is obsessed with his tail

by LC
(Camas WA)

My cat is obsessed with his tail! I recently changed my cat's diet to partially raw & Felidae All natural grade because of Bladder stones and struvite crystals. A few days ago his behavior has changed. He is obsessed with his tail as it continually flicks & he looks like he's agitated with it.

I noticed he is licking himself more than usual. He sometimes gets a distant look & one time he acted like he was watching something I couldn't see. I read somewhere that someone eliminated Felidae from the diet as it appeared it was an allergic reaction possibly because of the alfalfa & the cat improved.

I am beside myself because my cat has always been very healthy & happy (other than the Bladder stones and struvite crystals) and now he's not himself. I can tell by looking at his eyes something is NOT right. Does anyone have suggestions?