One of my chickens has feathers that seem to be disinegrating. The chook is 18 months old and all other eight chickens appear to be fine and in good health. The chook moulted but its feathers did not grow back and the ones that are left break off and appear to be disinegrating. It also appears very legargic and obviously is not well. Have checked for mites, ticks etc but none found, It is very scaly when touched all scales fly everywhere.