If you've got a prescription then you already have a pain Dr. Am I right, or is your family Dr prescribing them? If so, ask your family Dr to recommend a pain Dr. He/she should have a list of all different kinds of Drs.
Or, you can google pain Drs in your area and make some calls. Tell the nurse or receptionist when you call what you want to do so they can tell you if this Dr can help you get off of your pills.
You're very smart for not trying to do this on your own. You should have a tapering schedule.
Depending on where you are in No. CA, I have several PMP's who could help; I'm in the Sacramento area.
If you have insurance, it would be best to start there. Most insurance companies want you to find an in-network Dr.. Your company will provide you with a list.