I have similar symptoms. My pain is really almost exactly the same. I take liquid Tylenol (20ml) 3x per day. The pain has not disappeared, of course, but it has no edge or bite any more. I am able to tolerate it at this point. I consult with my Endocrinologist on this topic. She understands all the meds I'm on and says that if the Tylenol does enough it is ok in my system.

11/1999 SCC tongue - surgery
1/2000 Met(s) in lymph nodes - modRND
2/2000-4/2000 RT ~6 weeks
end of 2006 SCC tongue - surgery
1/2008 SCC BOT - surgery / PEG installed
2/2008 chemo & RT
4/2008 last time I consumed solid food by mouth