I don't know where you live, but you may want to contact the state vet lab to ask a few questions. In some states, necropsies are affordable, and many will euthanize at no extra cost. Each state is different. That way, you would get a diagnosis, and it might not be that expensive. It can be important to know if you have something in your flock that may affect others, such as Mycoplasma S. Gout is pretty rare, and can have many different causes, such as mold poisoning, too much protein, sodium, or calcium in the diet, and heredity. I have never seen it, though my roosters eat layer feed. I would give each suggestion of the other posters a consideration, and do what is best for you.