Anyone familiar with rashes?

[Southpaw]

Juno's got this rash:





It's been there maybe a couple weeks. I didn't think anything of it at first, figured it would just go away. She doesn't really seem irritated by it, occasionally she'll lick/chew at it, but not really any more frequently than she normally grooms herself. If I didn't know the rash was there, I wouldn't think she was behaving unusually. Although I'm sure it would help if she would just leave it alone completely.

Also if I touch it, it must make her itch or something because then she'll start wiggling around and then go to lick it.

Vet visit?