dear doctor, i had bad sunburn mark in my face 6 years back at my age of 24 , after the medication it was cleared completely and i have been using sunscreen ever since and was doing in-house job to avoid sun , somehow i happened to join a job depends outfield , within a few days under sun , i got back the black mark again in the same cheek areas , please advise me to remove this mark and to avoid in the future .