This is my first time posting. I've only recently gotten into raising chickens. I have an underweight hen. Let me get you the information which is suggested we provide. She is a 3 month old bantam cochin named Pillow. I am not sure of her weight but she is might lighter than her coop-mates and her breast bone is poking out. She is acting slower than the rest. She is not eating well. I only really noticed it today. She is so fluffly it's hard to tell. I feel like a bad chicken mama. She's the only one not scratching and not eating like food is going out of style. The only unusual thing which has been going on is I have another bird (Probably male, name is Fraggle Rock, or Mr Rock, or The Rock...) who I am treating for canker. None of the other birds are showing symptoms so I have not been giving them anything. Mr. Rock is another story though. I already have taken him to the vet but they are kinda scratching their head over a bird. I do think I will ask them to examine the yellow cheese balls I got out of his face under a microscope as they said they'd re-examine him for free. I digress.. I brought Pillow in to watch her and examine her droppings. She barely ate anything I offered her and didn't touch the water. I did have to soften her food with some water for her to eat at all. She only pooped a couple times, and they were all really tiny. The first one was watery too. I will post photos. As far as housing/bedding: They are in a smallish coop+run maybe three feet by 6 feet with their little upstairs coop area about 3x3 feet. I use pine pellets in there for bedding. They have the ground to scratch at all day. When I can I let them out to run around the yard, supervised. I suppose I want to know if i should be treating all of them for canker even though Mr. Rock is the only one with symptoms. Is Pillow's lack of eating and weight loss something else entirely, and what extra data would you need to recommend treatment?