I have been taking 30 mg. of oxy., 3X daily for over 2.5 yrs. I ...

I have been taking 30 mg. of oxy., 3X daily for over 2.5 yrs. I hate this stuff but I don't believe I could live through the back pain without it. I have severe constipation problems, weak/tired all the time, and my stomach is a mess. I can't eat anything like I use to, nor does the food taste as good. I would like to get off this stuff but the withdrawals are so bad that I sweet, my nerves are shot, and I really get angry at the slightes things. What can a person do? Your comments are appreciated.