My boyfriend resqued a calico kitten from the warehouse where he works. No mom to be found. She was about 6 weeks old when we got her. She was very cuddly and cute at first, we took her to the vet and they said everything was good with her health. Now she's around 12 weeks old and has become crazy. First of all, she doesn't seem to be that much bigger at all than when we first got her. She gets regular feedings of kitten food both wet and dry but hasn't really grown. Also she bites. Constantly. I'm not talking about play biting on toes and fingers while playing (although she does this too) but just bites constantly. She will come up to me and bite my arm, or any skin that's exposed and she does it hard! She has never broken the skin and we try and play with her with kitty toys but she always just goes for peoples skin when they aren't even playing with them. Just this morning she was attacking and biting my stomach. We have tried spray bottles but it just seems to get her mored riled up. Also sometimes she runs into walls so I think she has some sort of slowness. Anyone have any advice?

I have heard from people who had a similar cat that the mother was feral and probably had distemper. Their cat was totally insane, attacking ankles, leaping up to bite necks, slamming into a door over and over, etc. The vet told them there was no cure.

You have to remember that 'Play' to a kitten (and older cat) means 'hunting'. All play time revolves around that.

I suspect you are reinforcing that instinct by playing with the traditional cat toys... something on a string? Or like your hand, moving under something, like maybe a mouse?
Not a good idea. Her biting is still part of playing; if she wanted to, she could probably take a small chunk out of your arm or leg with those sharp kitten teeth.

It doesn't take long for a cat to turn, or revert, to 'feral', once abandoned. Hard Times teach harsh lessons. Kittens from such a cat start nearly undomesticated, and have to learn how to act around people. Sometimes it doesn't sink in. Recent studies in cat behavior have shown that kittens who are without maternal and litter mate interaction before 6 weeks of age can sometimes develop serious antisocial behavior, bordering on violent with human family members.

My cat was wild and crazy at first , he lived in the ditch down the road until I caught him and brought him home , he was so wild when I first got him he would bite anytime you got close . He would just jump and run into things all the time . It was so bad we named him crackhead , it took about a year of TLC , but we have had him for 5 years now , and he's a great cat,
It might take awhile for the kitty to come around give her a chance before you get rid of her.
Good Luck