ok, i just read the rest of the comments, lol sorry. Glad he got the peg. And yes, he should not be brushing his tongue during radiation. The top layer is essentially being burned off, and the peeling is understandable cuz he brushed it!! I was told not to go anywhere near my tongue when brushing.. and i still don't brush it and am 4 months out of radiation.
So no more brushing the tongue... i don't know what they will do now that it is bleeding, may stop treatment for a while to try to let it heal, but no matter what they do, i hope no more problems like that come up!!
Also maybe getting a extra soft/sensitive or baby toothbrush. That is what my rad onc told me to get as the bristles are much softer and even that still hurt towards the end, but i noticed a big difference when i switched to it.

Keep up the good fight!!