Hen with swollen toe and black scab - Bumblefoot?

[Eglanterina]

My hen has a toe that is warm to the touch and swollen, and she does not like to stand on that foot. There appears to be a black scab forming on the underside of the swollen toe adjacent to the nail. You'll see from the photos that we've struggled with scaly leg mite infections this past winter. Any thoughts about this being Bumblefoot or perhaps an issue related to the scaly leg mite problem?

 

[azygous]

What you are seeing in real time is auto-amputation. An injury to an extremity on a chicken will swell, cut off the blood supply to the injured tip, causing it to dry out, turn black and fall off.

There is nothing you need to do except admire the efficiency of a chicken's body.