My hens aren't acting normal

Chickens often stop laying after a change in their routine - addition or subtraction of flock members, a predator attack, etc. But I am think parasites with the feather loss. Give you a close inspection - and the others ones as well. Good luck to you!

 

Molting hens can look pretty awful, some go almost naked but with others, if it where not for feathers floating around in the coop, you might hardly notice it at all. Either extreme they will slow and even stop laying for 2-3 weeks then gradually return to normal.

Add some protein to their diet (perhaps a nice scrambled egg?) and put some vitamin drops to the water. I use drops made for human babies. Molting is hard enough on a chicken so I don't add to their stress by worm or chemically treating for parasites unless I can actually see them.

As for your other hens,even if they are not molting very hot or humid weather can slow or stop laying but if they are all about the same age it is possible that they are also at some stage of molting as well.