I know a woman who had something very similar to that, and she was diagnosed with yeast (candida). The doctor said she got it from using a lot of cutlery from restaurants....(don't know if that's true).
They gave her Antibiotics , and I don't think that worked well. She was home from work for about 3 weeks.
Sorry I couldn't be of more help, but I very vividly remember her going through that....
Could candida be the problem?
Oil pulling has a very healing, de-sensitizing effect, so maybe it will help. He must not, under any circumstances, swallow any oil, and I would only do it for 5 minutes at a time.....don't know why I feel that way, it just sounds right though.