Fixation on spots and poor skin

Hi all

I have a 16 year old totally fixating on his skin. He has very few spots and has greatly improved skin after 6 months of antibiotics. He is struggling mentally and is in a really low place today. He hates himself and has started to spit. Is there anything I can do to help him? He has not touched dairy or sugar for 2 years and says his poor skin is ruining his life and makes him 'not normal' I feel inept and don't know what to do for the best. Feeling lonely and tearful