i have a 2 year old tufted roman goose. she has been laying normally all spring but i dont think she ever set. this week i have noticed that she is very week with dirty feathers, she also stands with her head tuck under her wing. her and her gander have free range of 5 arces yard, she has never been sick alway strong and healthy. i have noticed her stick her head up in the air and swallow a few times even when they are not near water. i was giving them a treat that they usually love and she tripped and just about didn't recover. any ideas on what is going on or what i need to do?