Why is my chick fluffed up

[Zoom Zoom]

I have an 11 month old BO hen who has started fluffing her feathers almost constantly.She looks like she did when it was so cold and she was trying to stay warm. She is eating, drinking and running around doing what chickens do - she seems healthy. She also lays an egg daily. I checked her from beak to tail today and found no signs of mites/lice or anything looking unusual. Her poops are a bit runny but that's something I've been dealing with since November. She was wormed in November. I have five other hens and a roo and none of them are fluffing their feathers. Is this something I should be concerned about? Is there something I should check for? Anything I should do. Thanks.

 

[enola]

What wormer did you use?