Alan was suffering from lots of what he described as "gunk" in his mouth I read somewhere that papaya juice helpful for the mucus and inflammation and after about three weeks seems to be helping.
Also read an article about a new treatment post radiotherapy called Photobiomodulation (PBM). My nephew who's 8 months post radiotherapy for head & Neck cancer is being offered a trial at some point.
I think a hospital in Essex using with great success.?