I have a senseless dry and black rash on my neck for a long. What is that?

Hello doctor,

I am a 19-year-old male. I am active and never had any serious condition of unhealthiness. As a part of the ongoing project, I had to work for almost 14 days in the burning hot sun. When I returned home, I identified white spots on my face and quickly searched the internet for a narrow down of the condition. Thanks to this site. I have identified it as tinea versicolor and used an OTC Clotrimazole ointment and it faded away in less than a week.

Just after that, my friends pointed out a rash on my neck and I thought it was probably the same as my previous infection. It was white in color and looked like a fungal infection with four small patches. And so I applied the same cream. Unfortunately, I could observe no change and kept trying home remedies like turmeric and honey paste, etc. It has now come to look black and dry as in the attached image. There is no sensation whatsoever at all. I only know it is there when I place my hand over it. Please, can you help me identify what it is? I have already looked at a lot of conditions and was unable to match them with mine. It is been almost six months and it looks like one has faded and the other three have mated.