Scratch behind ears

Hello everyone. Please help me my 8months kitten scratches behind his ears and loose some hair too. Red skin also visible. I don't know what to do. Can anyone tell me what is it and what to do?

Does he normally wear a collar?  If so, it could be something in the collar that is causing him to itch.  OR, could be fleas, or just one single flea bite because he could be allergic to them.  OR, it could be food.  Cats who have food allergies often will itch about their heads and necks.  What are feeding him (exact brand and type?)  Or, it could be something else...I'm just tossing out some of the most common things

My cat just had to go to the vet for a scratch and it turned out she did it because of an ear infection. Can you take your kitten to the vet and see if they can give an exam and figure out what's going on? If not then definitely check for fleas with a flea comb, check the ear for black gunk that would indicate an infection, and trying switching to single ingredient food to see if it's food allergy related.