That really doesn't sound fun at all, and i understand the worry. Every now and then, i get white patches on my tongue that show up and i am 6 months out of treatment, but they go away usually within 2 weeks and don't hurt. But that it's spreading makes me wonder. It sounds like thrush, but thrush meds didn't help. they also had him on antibiotics for his infection in his neck, but what kind of anti's did they have him on? Pill form, or IV? Do you know the name of the anti's? When I had a staph infection in my neck it popped open like 3 weeks after my neck dissection, but they put me on iv anti's i don't remember the name, i know it started with a c, and they had me on iv for 3 days, and then they had me on pill form for 10 days after and it didn't start getting better swelling wise until the 7th day of pills. But I really don't know what to tell you.
The Mayo is a CCC and they are one of the best in MN for oral cancer. But I go to U of M and I see one of the top rated oral surgeons in MN for oral cancer, and he's always taken care of any little issue i've had.
I wish you luck and hopefully you get this figured out asap, sorry i couldn't really be of much help!! I know my sores didn't go away from radiation until like 2 months after, but he said they don't hurt. Mine hurt but eventually stopped hurting but were still slightly whiteish pink for about 2 weeks or so after they stopped hurting.