That appears to be footpad dermatitis, which is caused by walking around in mud, wet spots, and soiled bedding. Bumblefoot is a localised version. It can be also caused by diets high in corn and soy. What are you feeding? Do you have problems with drainage or mud? I would soak his feet in warm Epsom salts or soapy wtare and dry them well. Spending some time on a dry towel in a dog crate with food ans water might give them a chance to heal. B complex vitamins 1/4 to 1/2 tablet daily crushed into his feed might also help. Here is some reading about the condition:
https://www.farmhealthonline.com/US/disease-management/poultry-diseases/footpad-dermatitis/