Why Did I Get a Brown Mark Immediately After Chemical Peel?

I tried the Jessner peel yesterday for acne scars, and am quite worried about the dark brown color on my face. I put on one layer. I neutralized it with a cold wet towel after 10 seconds - too much pain. There was frosting on one side. After half an hour, it turned into the dark brown mark I now have. Even my chin and neck, which didn't frost, also have dark spots. Forums say my skin should become brown before peeling, but I am not even close to peeling. Is this PIH? Is this mark permanent?