I get it too, but I typically get it under my shorts on the tops of my thighs. It looks just just like yours. It doesn't hurt, does not itch. And it goes away in a day or so. Since I put sun block on my whole legs, and only get the rash in the area covered by my bike shorts, I'm thinking that it is just a simple heat rash and that nothing really needs to be done. But if anyone has found a way to prevent it, or to make it go away faster, I'd love to hear.