Thank you for your question. It sounds like you have a mild burn, the dark area could be the skin still healing at this point. The best thing you can do is keep the area hydrated by using a heavy moisturizer product or an Aquaphor on that area, also be sure to avoid the sun and wear sunscreen to prevent further damage while the skin is healing. The burnt area could take 3 to 5 months to heal entirely so just be sure to take care of it. I would recommend having a consult with your aesthetician or dermatologist during this time, it is hard to say what needs to be done without actually seeing the damage.