I am by no means an expert. I have a hen who had Bumblefoot. It is usually an abscess that a callous eventually grows over it...keeping it from draining. I t is usually a staff infection. Can be caused by the foot getting injured on a sharp object. You can give 1/2 of a baby aspirin for comfort once a day. I did daily soaks in warm water with Epsom salts, and massaged the lump while in the water. I never saw anything come out, but she stopped limping and seems fine now. I soaked her for about 4 days, when she got better. Hope this helps.