HELP i've been stupid 10 points ?

Hi sometime this week I used a flannel which I had not used in ages and did not realize it had demestos on. I used it on my face on my cheeks. Its started to burn. I thought it would heal by itself but it hasn't my skin is now starting to flake and peel. My mum is a worrier and I won't tell her becuase I am 15 lol and was very stupid. Please any ideas on what I can do. ???