Many people raise roosters with hens on layer feed. You are thinking of gout which is a problem with the kidneys. You need to get more calcium into your hens to see if the shells become more hard. Most chickens will swallow a calcium tablet if you open the beak and place it in the back on the throat. Some do use all flock, but it is important for the hens to take the crushed oyster shell and some use egg shells as well. It could be that she has a problem with her shell gland in the oviduct. If your other hens all have hard shells, that may be the problem.