Annabel,
6 weeks post radiation and my mom lived on those pain patches. She was up to wearing 4 at time the slowly weaned herself off of them and about a week and a half ago took the last patch off. She has some pain but no problems at all with the addiction part. They were a lifesaver for her and without them she wouldn't have been able to eat at all during treatment.
My mom has a dentist that her ENT referred her to that specializes in Oral Cancer patients. I'm surprised that nobody has given you a referral. My moms dentist is in Burbank. Let me know if you want his name.
Take care. I'm sure things will start looking up soon......
Danielle