I have a 5 month old pullet who in the past month seems to have become very weak, thin, pale comb, sits stagnant most of the day, very lethargic. Her sisters are much heavier, their combs are bright and red as they are coming close to laying, there is a definite difference. I have wormed her twice, checked her for lice and mites (found nothing) but dusted her anyhow as she never seems to jump in there and dust bathe with the others. I also treated her with permetherin drops just in case. I don't live where there is fowl tick...I am very perplexed. To me it would seem like some sort of parasite the way she is so weak and thin and pale. She is quarantined from the others. Ideas? I'm just worried she is going to wither away 
