Help! Kitten biting off own fur!

I just discovered that my 6 month old kitten has been bitting off his furr on his rear left leg !

He was neutered approx 3 weeks ago, and since that time he's been frequently "Cleaning" with his hind leg up over his head . I never thought anything of this as I figured he was just cleaning the area.

Tonight I noticed he hasnt been cleaning/grooming and actually been biting off his furr ! So bad to a point that its down to flesh and looks like it is about to/or already has been bleeding!

Why is he doing this???

How do I stop this behaviour ?

One of my girls is so allergic to flea bites that the first flea of the season will set her to doing that, just one bite will do it to her. If yours doesn't have fleas he might be allergic to something else. Maybe you should take him to the Vet. Good luck.

Fleas could the cause, but I would definitely take him to the vet ASAP.