my x battery hen Dora has been very down and sad looking the past two days. it was very sudden and now while all the others are free ranging she is just stood in the run with her head down. she also stands up a lot with her eyes closed and last night i caught her sleeping in the nest box fiddling with all the eggs. she is eating and drinking fine, but when i chucked meal worms out which she loves she didnt seem bothered and carried on standing there. any ideas?