I have 4 hens, 3 isa Browns, 1 Hamburg. They are all about 9 months old and lived together since August. All has been fine until the last 2 weeks, the Hamburg started laying and since then the others have been pecking her, her tail and back is bald and scabby, she keeps getting small bloody wound. At night they seem fine as they all sleep on the perch next to each other. I have tried putting mustard mixed with Vaseline on her back, purple spray,giving them cabbages etc to stop them getting bored but I went out again this morning and noticed them trying to peck her again. I have no way of isolating the hen but even if I did I am concerned about introducing her again. Any ideas? I also noticed she doesn't like to lay her eggs in the nest box like the others, she either lays on the floor of the coop or outside on the ground.