No doubt, as Canoe points out, there's very likely a dietary issue going on here, but there's almost always a behavioral issue(s) as well that ought to be considered. By the way, although I've never used Dumor Fee myself, I've seen it associated with problems of all kinds here on these forums. You might consider shelving the Dumor for a couple months and feed another brand and see if that might improve things.
If this Wheaten is the only such colored/patterned bird in the flock, chances are it's being singled out because of its differences. If the Wheaten is also very timid by temperament, it will aggravate her situation since the flock will sometimes prey on perceived weakness. A timid bird sometimes benefits from a "vacation" in an adjacent safe pen during the day. I had such a hen who became much better able to stand up for herself after her vacation in the "jail" pen for a month.
Along with that, a flock will also pick up on subtle injuries and illnesses that escape our notice until we start to think about it. Observe this Wheaten's behavior to make sure she's not ill or injured other than what the flock has done to her tail.
If you've addressed the dietary issue, and ruled out injury and illness, and the behavior doesn't seem to improve, sometimes it's necessary to diffuse the flock's focus on the Wheaten's different appearance by introducing more like her. It's far less likely that differences in appearance becomes an issue when there are numerous representatives of that particular breed in the flock.
They seem like it's so bad they are preventing her from good and water. What do I do? (The pic is before Blu-Kote)
