Double cr*p. Now the three of them have one on each foot! It must have been from the edge of that 2 x 2 that wasn't meant to be a roost bar.
Does anyone have a good way of bandaging a foot that keeps it clean and won't come off?
Slather the whole foot in triple antibiotic, then wrap with clean cotton gauze. Then finish by wrapping the gauze area in vet wrap or similar clinging bandage. If your chickens are outside, you will need to change the whole setup everyday to keep dirt out of the wound.