Hello Sarah and welcome.  Don't let your mind run riot; take things as they come (I realise it is easier said than done but you are just giving yourself more grief).   If, and it is still an "if" he  has a mouth cancer that is the time to plan for the  next move.    It may of course be nothing of the sort as there are other things it could be.  Just treat your dad in the loving way which I am sure you have been doing; don't add to your mum's stress and try to reassure her that it is best to take things one step at a time.  It won't help your mum or dad to have lots of stress flowing through the house.  I don't know if this is the cause for your mum's rash but - whatever it is - calm things down.  Even if - and there appears to be several steps to get through before anyone knows what is causing your dad's mouth problems, and a further "If" he refuses any treatment he would be kept comfortable and should not suffer.  People do refuse cancer and that can be a perfectly rational response.    Sorry if this post appears to be at all critical - it is not meant that way and  I could not say I would not be doing the same in your situation but I honestly think your best course of action is to just take each separate thing as you find out, then you can make some decisions with your mum and dad.  Annie

Thank you Annie. Not at all taken as criticism it’s good to have an unbiased view. We’re such a close family and as I work for myself I’m doing most of the fetching and carrying back and forth to the hospital. They’ve been together over 55 years and one does not function without the other as you can imagine so it’s hard to keep Mum calm as she’s a natural worrier . The growth in his mout looks just like images from the internet and I know Dr google is a bad thing but it’s hard not to do it. Thank you though Annie it’s nice to know people are kind enough to reply xx

Perhaps you could try to break thigns down into segments with your mum - talk it over with her.  Anyway, I am not going to harangue you further but just wanted to say please do come back if and when you have any more worries.  Annie