main thing to do is feed light eg depurative and seperate any that isnt looking good dont let them out to fly will only stress them firther if there not right get the droppings checked asap because you can be grasping at straws as to what people say it is on here it could be any number of things mate and as mickb says up there bin anything thats bad dont take no chances have had bad experiences myself with youngings ... good luck mate hope this helps