I got some chickens this family didnt want anymore and one of them couldnt walk properly or at all and looked extermley obese we tried to make him lose some weight. And walk around more but he died shortly after and now one of the underweight chickens is experiencing the same issue except she wont eat or drink and her wings are limp and even though she you can feel all her bones and no muscle or weight she has a huge soft belly that looks like its going to pop and she looks like she is going to die any minute idk if its mareks or if shes old (she looks very young).