Need advice - friend's cat with many problems

Hello PT. My friend has a cat who has some serious issues and she's at a loss, and I'm hoping someone here can help.

She hasn't had him for long. He was adopted from the SPCA. He's a long haired siamese-ish looking cat, but with no history she's not sure if he's a Birman or? When she got him, he was all 4 paws declawed and quite frankly whoever did it was a pretty botch doctor.. they look mutilated.

He's had behaviour issues from the start. He goes through phases of not eating - for days. They've finally been able to determine that he has severe food allergies and is now on a hypoallergenic food. He eats a can a day, no dry, but is very very skinny. Recently, he's starting exhibiting signs of Pica. He's destroyed her couch - he's chewed through all 4 corners and along the front panels and has started going through the pillows. What's interesting is every time he eats the couch he goes back and eats his cat food. It seems to be related in some way. He also eats any plastic, goes through the garbages to get to plastic, through any wires (speakers, headphones, chargers, you name it) and actually injested ball of tin foil about the size of a ping pong ball, which thanfully came back up. He's also chewed through a roll of toilet paper.

The other weird thing she's noticed is that he's scratching at his jaw a lot. He also eats really weird, almost like food gets stuck. He doesn't have any pain when palpated and there's nothing visible.

Does anyone have any ideas about this? She's taken him to the vet and besides the allergies, nothing was found. I gave her Nancy Efrusy's email and she's emailed now at least 3 times but Nancy has never responded, so if anyone knows of any other pet communicators that have been helpful please let me know. She's desperate to know what's going on.

Any advice would be appreciated!

I am a regular on a pet radio show, All Paws Pet Talk, and there are several animal communicators on the "Animal Experts" - see http://AllPawsPetTalk.com - you can go to the Animal Experts page to see the different people, or even ask a question right there on the homepage.

Also, as a human with food allergies, I know there is no such thing as generically "hypoallergenic" food. She should probably start him on an "elimination" diet - feed him simple things, like plain boiled chicken, and see how he reacts to that. All the issues could be related to the food allergies - as sometimes it makes the mouth feel itchy, and chewing on something relieves that.

It may take some time to figure out what is safe for him to eat, but starting with just chicken, and then adding some rice, and seeing if things calm down, will then enable her to slowly add other things, cautiously, one ingredient at a time, until she knows what is causing his issues. Has a vet checked those poor paws? Is it possible he has nerve damage that is causing the poor thing constant discomfort that could maybe be remedied?