I have a 5 month old kitten who is an outside kitty. I do let him in sometimes. When he's in, he is constantly kneading. He does this on my feet which really hurts. If he stops walking, he starts kneading on the floor. He can be sitting by the cat dish and he will start kneading before he starts eating. And of course he does it when you pick him up. Any ideas why he does this so much?