Sir, Recently Due Hectic Schedule I Was Exposed To Sunlight

Sir, recently due hectic schedule I was exposed to sunlight for 12 hours everyday. Just to save the face from getting tan, I tied a nylon mask covering my lower area face, which I think was too tight. After some hours, the same area turned red. Now when I am back the effected area turned black. This discolouration is worrying me. Plz advice some medicine to clear the black patch.