Be very glad you're not on methadone. As the other response stated, it has an extremely long duration. Oxycodone produces some pretty nasty chills upon withdrawal, so this is normal. You'll also lack energy, feel weak, possibly depressed and listless, sweat, feel anxious and just bad in general. You have the tools you need to get off this stuff. I've found it useful to find out the minimal amount it takes to alleviate discontinuation symptoms.. Usually about 2/3 of your usual dose. Just keep increasing your dose intervals...and decreasing the dose every few days. Let yourself be uncomfortable for awhile, then take just enough to feel some relief. It'll take some time but with determination, willpower and a plan...you'll be off the stuff with minimal discomfort. My own note, quitting suddenly has you pretty much bedbound for 2 to 3 days but you bounce back pretty quickly. Where as the slow taper allows you to stay functional and feeling decent but it takes longer to reach your goal. I personally recommend tapering; it's much easier on your brain and body.
Also, at 6mg of Xanax a day, this should help the anxiety associated with quitting Percocet. Just listen to your body and do your taper nice and slow!
This is why we push aftercare. If one is a Addict they have a disease, and like any disease we need help and support. I do wish you the best and you will be so much better off these in the long run. Your mind will be thinking so much clearer, but it will take time and patience.
Wishing you the best!
Vickie