Hello I am 26 .what happened is I recognize black patch inside my mouth on inside cheek wall small coin sized like skin melanosis. I just research about it. I found it causes by smoking but I do not smoke and do not drink .i do not know how long it has been I saw it 2 days before and the skin is like slightly rough than normal skin. I want to tell you that 7 days ago it was not there. After that I chewed limcee vitamin c tablet and instead of chewing it on my tongue I just kept it on side my cheek at that point I felt like dryness on that point. I am not sure is the black patch is because of that .or something else please tell me. I heard that vitamin c tablet contains some acids in it. By putting so long on my cheek can it cause that burning black patch. please tell me. i cant send pic but it is sane like mouth melanosis. please tell me why this. And causes of this.