Hand, foot and mouth...peeling bum

[HHH3]

DS2 (13 months) has hfm. He's got loads of spots/blisters but his bum is the worst - they've all joined up so it's all red. However it doesn't seem to be bothering him at all.

But he's just had a long play in the bath and when I was drying him the skin on his bum started to peel. He didn't seem bothered by it but is it normal?

Slather him with zinc and caster oil, I mean trowel it on. Leave nappy off when poss. My daughter was like this. Doc told me to ditch terry nappies ( terrible idea) and let her botty breath,

I meant terry's are a bad thing, not doc's advice