Hi William,
I have a similar problem with percocet as you do. I was on vicodin for 2 months, and it became innefective. I am now taking 2-3 percocet every 4 hours for neck pain...my surgery is in 3 weeks. I also have a fentanyl patch, which may be appropriate for you. I have noticed that the percocet is not working as well as it did at first. One thing you should ask your doctor is if he will give you just oxycodone instead of percocet. it is the same...just without the added tylenol...which is hard on your liver.
hope this helps,
Dave