Kristin,
No it's not normal to be on pain meds for 2 years. The doctors need to find the cause of the pain and treat it. Tooth decay is bad news if she has had radiation. An extraction, post radiation, can cause many complications such as Osteoradianecrosis. She needs to see a dentist every 4 months for cleaning, use dental trays with flouride treatments regularly and practice rigorous dental hygiene. This is a lifetime risk after radiation. Like David said, you may want to find a dental oncologist -especially if extractions are required.

The tongue swelling doesn't sound right - when is the last time she saw the ENT or head & neck surgeon and what does he say about it?

I have 9 years sober myself - alcoholics suffer pain too.