For the past week or so, one of my sexlink hens has been laying a thin-shelled, rough-like-sandpaper egg. That must be OUCH to push out! I don't know which girl it is, could this be a sign of ill-health? All has been fine until now... the only change in diet has been no more free-ranging since the ground is frozen and covered in snow and ice. All other 7 laying hens in the coop have perfect, smooth, hard-shelled eggs and they all share the same food. Any ideas what could be wrong? Thank you!