Hi there..
Well I'm not sure - but others may be along to give you some advice. The cutaneous mets I've heard of are usually in the neck region - related to extra capular extension, and node involvement. I haven't heard about it on the face though I would expect that if it were it would be rash like and confined to one area rather than all over (or in different areas) it sounds to me like acne or as you said maybe a reaction to food. Now remember you've been through radiation and frankly this soon out your skin is still not normal... So if you do have acne or a break out your skin may not behave the same way it used to. Also cancer isnt something That would heal, so if they do clear up, chances are its no cancer.

But do have it checked out and best of luck.