May not be exactly bumblefoot. There are some subtle differences, but I don't think the treatment will be significantly different.
I suspect Wallace has an infection from the wound. We know what ducks walk around in . . . . they can pick up bacteria in cuts quite easily.
A photo would help.
Hydrogen peroxide is often good at first, but in this case, I would soak the foot in warm, not hot, Epsom salt water. Do not just add E.s. to bathwater - it is a laxative, and you don't want Wallace drinking it.
Either put Epsom salt water in a flat-bottomed shallow bucket or bowl and stand him in it for a while, or make a compress and wrap the foot. You could let him swim in lukewarm water for a while first to soften the skin a bit.
Then you could either rub antibiotic ointment (without painkiller) on the foot and leg, or place a couple of drops of clear (clear, clear, not brown) iodine on the bump. Let it be for five days or so. With bumblefoot, the spot where the clear iodine was placed forms a black scab. The foot is then soaked again, and when the scab is softened it can be very gently pulled, and the yuck comes out with the scab.
If it's bleeding, sounds to me like it's not healing right. I would get Wallace into sick bay for a few days while treating him, and I might lean toward the antibiotic ointment method. It may not be a bumble, it could be a hematoma (nasty bruise). So I would do Epsom salt compress three times a day, and keep him quiet, with fresh water and food.
