I'm sorry to hear what you are dealing with, but you have made the first step, admitting you have a problem!!
I had a family member addicted to pain killers and the only way he could stop is to go into treatment. Withdrawals can be horrible and you should not stop your meds unless you are under the care of a medical facility.
Contact your local hospital or treatment center. Don't do it alone. You need a professional that can help and give you meds for withdrawal and monitor you very closely. If you can't miss work they may have options for you. But I think you will need to be in treatment because of your withdrawals.
Do you not want to call and tell your parents or other family members you need help? They may be able to assist you financially until you get on your feet. You may be surprised how supportive they will be.
Did you check with your HR dept at work to see if they have a program for addiction? If you have insurance they should cover it. Tell them you will take time off without pay. This is your life and you must think of yourself.
The family member that went in for treatment had back pain. He found out that the back pain was from the pain killers over time. Though he started the pain killers for a back injury they said one of the side effects of long term use is body aches, and possible back pain.
Keep us posted! You can do this!!
Blessings,
Leslie