It looks like Pododermatitis.
I would soak/clean up the foot with chlorhexidine or povidone iodine. Let dry, then apply a thin layer triple antibiotic ointment to the rough area and lump at the back of the foot, not the whole foot pad. Wrap the foot. You may need to cushion the pad with a small piece of gauze, then wrap.
Repeat the process for a couple of days. See if this softens up that protruding part and if it will loosen up. This does not look like a foot I would cut into at this point, I would treat it with soaking and ointment for several days.
It may sound counterintuitive to only apply ointment to that roughened area, but I've found that keeping a whole foot moist with ointment seems to soften the tissue too much, or it did with mine.
If the swelling doesn't go down but the rough area softens up, you can try soaking in Tricide Neo, this will help with infection.
https://www.backyardchickens.com/threads/treating-bumblefoot-with-tricide-neo.513183/post-6526194
https://www.koiacres.com/p/tricide-neo.html