Penis rash for over a month

Not sure if it’s an std or not. Rash changes throughout the day and I’ve noticed it for the past month. At times it feels like there’s an ache/burn feeling on the skin of the head of my penis. But when I have pain and then look at my penis the rash doesn’t necessarily show up where I’m feeling the pain. 

 

 Have a similar issue. Let me know if you figure out what it is!