Non healing ulcer in throat after radiation tx

Sorry in advance for the long post.  I finished my treatment on November 5 of last year with 35 rounds of radiation and 6 rounds of Erbitux for Tonsil cancer- primary tumor was in tonsil and had spread to a few lymph nodes on both sides.  Everything during the treatment went good except the radiation doctor at MD Anderson noticed there was a hole in my throat where the primary tumor was about 5 weeks in which he called a fistula.  At first he was excited that the tumor was gone and said that was a good sign.  Finished my treatment and was slowly healing in November.  In December, I took a turn for the worse and was feeling bad.  The back of my throat was very sore and swollen, the swelling had gone all the way down to my checks, that the pain patch or pain medicine could not relieve the pain.  The day after Christmas my wife and I decided to go the ER at MD Anderson.  They did an Xray and a CAT which showed alot of activity but there was no new tumors.  The doctor felt the CT scan was indicative of an infection so he decided to put me on IV and gave me some antibiotics.  I felt much better and then about a week after the antibiotics were complete, the infection in throat started to hurt again and the cheek started swelling.  Ended up going back to the ER since it was on a Sunday and did not want to deal with the pain anymore.  They really did not do any CAT scans or X-rays, just asked what was going on and we told him and the doc just decided to give us another round of antibiotics which was great.  I got back on them, felt good enough and my energy levels were high enough to go to work a couple of days.  I even hit some golf balls and saw a movie with no issues of soreness.  I quit taking antibiotics on Sunday and then on Tuesday, starting feeling crap again.  We decided to go see the radiation doctor and he looked at it and said he thinks it is a severe ulcer next to the hole in my throat that won't heal.  He thinks since food gets stuck the in the fistula or hole, it sits there an breeds bacteria which creates infection.  So he gave another prescription of antibiotics, but this time for 2 weeks.  I felt much better today and swelling went down, so I don't really think it is from a new tumor since it reacted to the antibiotics although that thought is in the back of my head which I have been trying to fight off.  Just wanted to know if anyone else experienced this or any advice to give would be so helpful.   Getting  tired of not feeling good.  Thanks Todd