We have a six-month old Rhode Island Red that has quit laying. Her comb is floppy, shriveled-looking and pale. She is a lot less active than my other 5 chickens, and we often find her laying in the corner of the coop when it is hot outside. She is able to get around well enough - eats, drinks, goes inside at night, etc. though she is kind of clumsy and un-coordinated. Her eyes, nose, and ears look OK. Also her vent is clean so I don't think she is having abnormal poops. Any ideas?