chronic rash and sweating months after treatment

Hello all,

I'm posting on behalf of my dad who underwent successful (we hope) radiotherapy treatment for a tumour in his sinuses last year. The radiotherapy that followed surgery was completed 6 months ago but he has been suffering from a severe rash and chronic sweating which has been slowly getting worse and worse over the last few months. The rash has slowly expanded to cover pretty much his whole body and is very red and itchy, and the swaeting began sporadically but is now so frequent that he gets through several sets of clothes a day and cannot sleep at night.

I'm hoping that someone here may know of someone who has experienced similar problems and found the cause and a solution, as the doctors here (we are in the UK) have so far been unable to find the cause or cure for it and life is becoming more unbearable for my dad now than during his treatment. It sounds as if it's an extremely rare scenario.

I'll leave the description at that for now but if anyone has any knowledge that may help then I can certainly provide more details of his symptoms and situation.

Thank you,