Hi,
I hope you are ready for this as you really have got some problems there!
When you say that your dog has constant attention I hope you mean she has company all day and not what you actually said. To give a dog constant attention is rather like having a stalker!
First and foremost check her out at the vet.
As you have probably already done this, I think you know what has to be done, don't give her attention when she is biting herself. Sounds easy - it's not!
Your dog has learned that all she has to do is start nibbling and she will be rewarded with petting, or as she will see it, praise. She is controlling you and being rewarded for it and life doesn't get much better.
To stop her thinking this way a few things will have to change;
Prepare well, explain to all members of the household and regular visitors what you are doing, why and that everyone MUST do exactly the same things ALL the time with NO exceptions. It is in the dogs best interest.
Acquire a dozen or so small plastic bottles with screw top lids, small drink bottles are ideal. Put 6 or 7 small stones in each one.
Agree a day when treatment is going to start and make sure everyone knows!
Greet your dogs in the morning by asking them to sit before you make any physical contact with them. As soon as they obey pet them as much as you like. It is important to remember this as it is the key to this method working - you decide when the dogs are petted not them. Do not allow anyone to pet them unless the dogs have done something to earn it or are lying quietly and not chewing. Treat both dogs in the same way.
Whoever is in the house should have 2 or 3 of the prepared bottles to hand AT ALL TIMES. As soon as the dog starts to chew, whoever is supposed to be paying attention to her should throw, with some force, a bottle onto the floor close to her. Totally ignore any reaction and don't look at her. If she comes to you for reassurance tell her to go and lie down. Don't pet her and don't look at her. If she stops the chewing for 5 seconds after the bottle is thrown then you go to her and praise her calmly and gently, picking up the bottle at the same time and leaving her where she was. If she then refrains from chewing for 10 seconds before a bottle is thrown go back and praise her quietly again. If she is still behaving wait 15 seconds and praise, then 20, 25, 30 and so on. Ignore her totally in between times.
If she starts to chew before the time is up you must throw another bottle and wait for 5 seconds again.
Try to keep your other dog out of the way for a few days, in another room or staying with a friend except in situations where your bitch never chews such as on walks.
This does work although you have to 100% commited to it. Your dog will be a lot happier with this problem sorted and you will have a much healthier relationship with her. Good luck, let me know how it goes.