Hello Duchess,
Sorry for your brothers diagnosis and treatment complications.
Regarding the PEG tube irritation, in the US they have an ointment called Calmoseptine. (see
https://oley.org/page/CalmingRashes )
It is a zinc oxide skin protectant with some soothing menthol I think. Has calamine, zinc oxide, lanolin I think and some other ingrediants.
A doctor prescribed some for me for another issue, but it worked great on my skin in a sensitive area.
I'd suggest he ask his doctors about that or something similar.
Best wishes for his recovery,
R/
CQ