Donnajean, I really cannot remember how long my mouth sores lasted, but I know it was at least a month. The point I want to make here is that if his mouth smells the least bit bad, or "off" get him to a doc for some antibiotics immediately. Same thing if he is running a temp. I ended up in isolation for 8 days because my mouth got infected and I had no white cells due to chemo. This was the only scary part of the entire adventure, and happened two days after I was celebrating being all done. Do keep a close eye on those sores.
Joanna