I'm trying to determine your ammonia level that your chickens are dealing with. From what you've mentioned of your routine I can see your chickens developing issues.
As for the feed, my concerns would be mold developing around there feed stations exposure to it can be dangerous for chickens...
Your feeding her correctly, using a high protein feed turned into mash will give her faster digestion.
Generally you want several feeding and watering stations for a flock of birds to deter one chicken hoarding it.
And sorry if your flock is going through Mareks.