I would first try soaking the foot in either an Epsom salt or chlorhexidine mixture, to loosen the scab on her middle digit toe, then try to peel it off with a pair of tweezers, or/ if needed a scalpel. You can then apply an ointment to the area like Silver Silvadene cream, wrap gauze around, and bandage.
There are a few more areas, that appear swelled, but it doesn't look too far developed where surgery would be needed. In addition to soaking, and bandaging the foot, you can apply to dilute DMSO to the sores to reduce swelling.
Bumblefoot can be brought on by several factors, but rough/unforgiving bedding that slowly degrades the plantar surface, resulting in flaking can cause bacteria to enter. Ensuring her pen area is soft, and free of things it may get poked on can reduce problem from happening again in the future.
