I noticed around a month ago that my left wrist's skin colour has changed. It's now darker than the surrounding usual skin. And the skin looks dry and rather scaly. However, it's not itchy or painful. I am not sure why my skin became like this, but  from April, I was putting Voltaren gel on the area for my wrist issues. I used Voltaren for a month before stopping, and I think it might be related. For few months, I've been putting magnesium oil on my hands and wrists, but only my left wrist's skin seems affected, so I'm not sure if it's because of the magnesium oil.I don't wear a watch and I don't think I scratched myself. Please tell me the name of this skin condition and how to treat it (for example, creams). For example, can I put 1%  hydrocortisone on it or 99% aloe vera gel? Also, should I use an exfoliating soap or vitamin C moisturizer, or would it make it worse?