Hi Gretchen,
The sores and difficulty eating started on the 3rd week, and by the end of the 4th week he couldn't eat at all. He got thrush as well and his gums and tongue were covered in what looked like white moss. It went away with antibiotics.
Make sure John eats as much as he can while he can, and tell him not to wait too long if he has trouble swallowing and eating. He can still do stuff with a PEG (we moved house while he still had the PEG). It will just stop him loosing weight, and weight lost seems really hard to gain again.
Best wishes
Cecilia