There is no chilblain on the heel. It itches especially when it's hot. What happened?

It's frostbite, but it's not broken or caked. Keep warm. As long as it is warm for a few days, the weather will get better. No matter how good the medicine is, it can't be cured. If you don't work, or the place where you work is warm, you will get better soon.

If you can't sleep because of itching, start scalding with boiling water. It feels a little painful, and it won't itch at night.