I have this rash on my neck and can't figure out what it is.?

It started with just two small patches on either side of my neck when I used to wear this necklace all the time. Then they got bigger so I stopped wearing the necklace. But it never went away after than and over time it has gotten bigger so that it is a ring that goes around my entire neck. It usually is only a shade or two darker than my skin color so you don't really notice it but when it's hot it gets really red. Also sometimes it gets really dry and flaky which sucks if I am wearing a dark color because it looks like I have dandruff. I don't have insurance so I can't really go to a doctor and find out what it is. I was just hoping it mind sound familiar to someone or maybe some people had some suggestions as to treatments I could try...