I purchased blue orpington eggs. They hatched out and there was this little black one, sort of the runt but fluffy. All the chicks are now 5 weeks old and this little black one has poorly developed feathers- she looks like a vulture, and I felt her tonight and she is skinny. Could she have something? Her feathers are clean, but it looks like she has a little bit of dry skin (not moving, or like lice). I don't remember the breeder saying they were NPIP certified or anything like that. What does all that mean, could she have something contagious? She runs around just fine and seems to be happy, she is just still runty and very sad looking- like someone plucked half her feathers out. I'm still newer to all this so I appreciate help. Also- what should I use for a dust bath? I feel like the play sand isn't light enough. They really never dust bath in it (we are talking the older chickens now- like 4 months old). Should it be more like silica sand? Do I need to mix anything in with it? Should I put it in a pool? It's just in the run right now- the ground. Thanks everyone!!!