Do I have dandruff, because I'm not sure?

Good morning. For about two years I have stains on my back, in a darker color than the skin, you can say that they approach the color brown. They do not itch or in any way hurt, they do not flak. It looks to me like a dandruff of the spoils but I'm not entirely sure. The spots in winter are not so much visible, in summer they sharpen when it is hot and sweat, I will mention that I never sunbathe and always my back is covered from the sun. Can I lubricate them with pharmaceris bleaching cream 4% niacinamide (with papain and Vit. C) ? Is it better to use clotrimazole? I bought this one from Pharmaceris but I would like to make sure if it does not hurt if it is dandruff or something else.