Minh,
The same thing happened to me back in December. I had an ulcer show up and did not go away, this area also lit up on a PET scan. My ENT out me under to do a frozen section biopsy, and it was just radiation damage. I went through HBO to help get it healed. I was told that it was normal for something like that to take longer to heal, but good that I did not waste time in getting it checked because one never knows until it is. I am glad you went and had it checked. Go ahead and get into your regular ENT when he is back in the office, because he knows more about your history than his stand in.