cat biting way too much!

I have a cat who's about a year old. He's neutered and the only cat we have. We rescued him from animal services when he was about three months old and he was the sweetest thing. Now however he is being mean. He bites everywhere unprovoked. He doesn't scratch despite having all his claws. Just goes straight for biting. His ears pin back and he gets crazy hyper focused eyes and will literally jump for body parts and latch on. He goes for wrists, arms, elbows, fingers, feet, ankles and anything else he can get a grip on. He has a ton of toys that I switch periodically for others to keep him from being bored. He has a two condos and a scratch lounger. We also play with him all the time because he has so much energy. To stop the biting I've tried distracting him with toys and making loud sounds. I've tried time outs. I've tried ignoring him and or walking away but he just gets more riled up and follows nipping at my ankles. We even tried spray bottles. I'm running out of ideas. My husband and I have bite marks and scratches from his teeth all over our appendages. Please help! Any new ideas are very appreciated. We don't know what else to do.

Sometimes animals can become mean because there's a physical issue.  How long since he's been checked by a vet?  I would start there, just to make sure.

He was at the vet a month ago. When we first got him from the shelter he went all the time because he had an allergy from something in canned foods we couldn't figure out and would scratch and lick himself to the point where he had angry red patches that had fur missing. We switched to all different kinds of foods til finally we landed on rad cat and it seems to have stopped. His coat is all gleamy and the vet thought he was doing wonderfully.

It's great that you got the allergy under control.  That can be really tricky.

Is he an inside cat?  Sometimes cats can have redirected aggression.  Is there a chance there is a cat around outside that he can see?

He's an inside cat. We live on a fifth floor apartment so I don't know where he would see another cat. I thought it might be pent up energy so we play with him until he plops. I just can figure out how to make him realize that biting isn't ok. Saying NO! didn't work. It just made him more upset. Time outs just confuse him and I think he likes being in the bathroom bc he likes to open up the cabinets in there. When I try walking away he follows me nipping at my heels. I really don't like spraying him with water bc it just seems cruel but when I do spray his tail in desperation it stops him only for a second.

The only other obvious thing is boredom.  Even though you play with him a lot he may have excessive energy.. in fact I think you've pretty well said that.  It's really hard to know where to go from here. 

A big part of me is wondering whether he needs a cat friend, but that's always risky... You may not want two cats, and it may backfire.  But I have seen cats settle when they have a playmate.

Just one other thought.  Did this happen really quickly?  Is there anything you can think of that may have been happening as his behaviour changed?

And, you're quite right about the squirting.. water bottles are pretty counter-productive when it comes to training cats. http://www.thecatsite.com/a/cats-and-discipline-dont-mix

A couple of articles that may interest you

http://www.thecatsite.com/a/cat-aggression-toward-people

http://www.thecatsite.com/a/playtime-aggression

 Wow, this sounds hard for you. What I find unusual is how he was very different when you first adopted him.  Can you remember when he started to bite and to latch on and attack in this way?  This might help to give some clue to what has been happening.

I have a few questions:

How often is this happening?

Is he still that sweet thing you adopted the rest of the time or does he go off on his own or watch you from high / hiding places and sleep all the time?

When he gets that hyper focused gaze and ears pinned back how do you react?  Do you look away, step away, turn your back to him, meet his gaze and hold very still and possibly tell him 'no'?  Other?

When he latches on with an attack do you stay very still or move away or try to shake / lift him off?

The links @Mani  has given you have some good advice in them so I hope you have time to read them if you haven't already done so.  One thing that is very important is that your cat does not think you are being aggressive in response to their move, or that you are playing with them.  If you move at all with a highly excited cat they are likely to take the movement as play or aggression and it will aggravate the attack and prolong it.  Trying to remain calm and still, pushing very slightly in towards him once he has latched on and then freezing and holding your position is the best chance you have of him stopping what he is doing.  Please try to do this unless he is drawing blood.

It takes a lot of concentration and practice to stay calm and still with a full grown cat throwing himself at you and latching on but it is the only thing I have found to help train my boy who has been a hyper energetic biter from when I adopted him at 4 1/2 months.  I was lucky though in that he has never used claws at all, just teeth.  He still bites my arm for attention occasionally but only if I have been bad and ignored him, and he does jump at my head and jumps up at my shoulders and climbs on me but not nearly as often as he did: he learned that if he attacked from behind I couldn't see him so at least he doesn't leap at my face, and he knows I don't like that so he now jumps on me to climb rather than play attack.  I have to remove him from the room when I am doing things that I know over excite him like making beds because I know that is a trigger, as are Valerian toys.

I really hope you are able to get similar results with your cat as I know how scary Mouse was when he was younger and full of pent up energy.

I think this started two months ago. My husband thinks it's bc he outgrew his condo. I thought he was just in a teenage cat stage. It happens everyday now. Last night he latched onto my leg when I was leaving the room. Nice long bite scratch to show for it. I've tried to sit still when he does it but it hurts. He really sinks his teeth into me. When I sit at the table and he bites my toes it's easier to ignore him but even that doesn't stop him. He just bites someone else's toes. I wish there was a way to show him that it isn't ok to bite but like I've said I haven't figured one out. He is occasionally that sweet cat but most of the time he's running around or watching us from up high like you said. He loves to hang out on top of my bookshelves and dressers watching us. I even put a piece of carpet on top of it for him since he went up there so much.

For some reason his behaviour sounds more anxious to me than anything else, given that he has been seen by his vet recently.  Did you talk to the vet about his behaviour change?

It is difficult to identify what triggers anxiety or perhaps redirected aggression in cats sometimes but it is worth trying to think if anything might have changed for him around the time he started to behave in this way. It is also worth trying of the cat stress remedies like Feliway or flower remedies if you haven't already done this.  Keep in mind that they do not show any rapid change but more of an overall gradual reduction in stress behaviours.

I'm sorry I haven't come up with anything more helpful.