My right forearm occasionally gets this rash or whatever. It didn't start happening until recently.…

My right forearm occasionally gets this rash or whatever. It didn't start happening until recently. I have an appointment soon but want to get opinions. It will last for a day or two and will sometimes itch and burn but other times it don't. I have cortisone extra strength cream which only helps with the burning. There's no change in my everyday routine. It's spontaneous.