Thanks for posting your query to HCM.
You must be having dermatitis
as you mentioned.
You must avoid not only garlic and mushrooms but also fish, egg and sea foods.
You must use a moisturizer in the day and steroid in the night. steroids
must be rotated so that you will not develop resistance to a particular type of steroid.
These may be done only under supervision at your age. So please consult your dermatologist