She's dying. She very likely has brain damage from the lump, which could be a tumor or an injury. The symptoms you describe are the body shuttiing down preceding death. At this point, I euthanize.
I'm sorry she wasn't able to recover. If you can afford it, you could take her alive to your state lab and they will euthanize her and do a necropsy and tell you what the lump was and what caused it. This is important because if it's from an avian virus, it may have implications for the rest of your flock.