That lump can be an oil gland that they have which is used to keep their feathers in good health. Not for sure if that is it 100% but most likely so. Just keep it clean if you can like they suggested for a few days. If their is red blood in it they will peck anything red. It is good to have some blu kote spray or aerosol or product of something in the blu kote line to cover any bleeding that comes up with chickens because they will peck a bleeder to death. Vetericyn is the best line of products available on the market now in my opinion. You can order them on Amazon. They have a complete line of stuff for all animals and poultry for wound care of all types even eye care without an Rx. Some of it is pricey but worth it. I have it in my chicken and dog first aid box at home. Styptic powder is often red but it stops bleeding also fast but flour will also do the job in a pinch and it’s harmless and cheap.