I have a 4 year old Rhode Island Red that is having bright green poop. I have read until my head hurts about Mareks and symptoms. She looks great! Only symptoms are bright green poop and she does lay in the yard. However, she is still eating and drinking and seems fine. She has recently (past couple of months) become the low chicken in the pecking order. She is clearly afraid of the leader. Could this just be stress? Thanks for any help!