My name is***** and I am sorry to hear that Autumn has had such a strange change in behavior! Eating inappropriate items can lead to intestinal blockage and possibly poisoning (not to mention the property damage).
I would first consider taking her to your regular vet for an exam and blood work to ensure there is no metabolic cause for the inappropriate chewing. I would wonder about diabetes, inflammatory bowel disease, pancreas problems or cancer as possibilities. If that is normal, I would consider contacting an animal behavior specialist. Complex behavior problems can be challenging to treat and correct and I would recommend taking her to a Diplomat of the American College of Veterinary Behaviorists. These are veterinarians who have gone to three extra years of schooling to learn about cat behavior and specific training and medications (if needed) to help remedy undesirable behavior. To find a specialist near you check out their website at www.dacvb.org. (Per their website there are diplomats in Vancouver, Toronto, Montreal and Quebec City.)
In the mean time, I would evaluate her diet and ensure that she is getting enough protein. I recommend canned kitten food as the primary diet for all cats regardless of age because this will be the highest in protein. Dry foods do not contain enough protein for cats and they can have a voracious appetite trying to make up for the deficiency.
I would also try to reduce stress in the house the best you can. Do you have enough litter boxes (one for each cat in house plus one more)? Do you have several feeding stations? Are there any dogs in the house that could be causing stress to the cat? Does the cat have a room or area that is her own, where she can escape the kids to sleep, eat and toilet?
You can also consider the following products. They have been shown to reduce anxiety in cats and can help in some situations: Feliway Spray or diffuser, or Composure. Both of these are available on Amazon.
Good luck to you and Autumn,
I hope this answer helps you. Feel free to contact me if you have any further questions.
Kansas State University
College of Veterinary Medicine Class of 2001