Young Quaker parrot, feather damaging behavior

My Question:
I have an eight month old Quaker named Oscar. I named her Oscar because it suited her personality - I had her DNA'd and it turns out Oscar is a girl. There are a series of things which kind of all started in mid July.

Her cage was originally in an open area between the kitchen, living room and dining room. Part of the back of the cage was covered with a blanket, but she could see from the top portion (it is a dome top cage). I felt her cage should be positioned better and wanted it so that one side of the cage was against the wall so I moved her between two other parrots (a female Pionus and male Senegal). That did not seem to work very well because I noticed she started plucking her chest area so I immediately moved her cage back to where it was originally. The plucking stopped temporarily but after a few weeks, she started again, but only the left side of her body around the wing area. The plucking was getting worse and worse so I brought her to an avian vet. One additional thing that Oscar was doing was she was crying out in what I would assume to be pain, and either plucking a feather out or biting whatever was closest in frustration and then lifted her left foot up as if to alleviate pain.

My vet looked her over and because of some other signs of plucking on her left wing shoulder area, and the wildlife we have around our place/deck (squirrels, chipmunks, bluejays) plus the fact that we bring her outside with us, she asked that I do a mite/lice treatment and come back the following week. So, I went home, did the treatment, thorough cleaning of the cage etc. None of my other parrots show any signs of mites or plucking. A week later, on the follow up appointment, the area which she was plucking was getting a bit better. However she was still doing the crying out and then the lifting of the leg. I must say that the frequency had decreased somewhat. The Vet did an x-ray of Oscar, showed me her body parts etc. What she was looking for was any possible visual abnormality of the ovary -- thinking she might have a cyst or something. The ovary was fine and there were no signs of lung infection etc. She said there was nothing in the x-ray that would be considered abnormal or out of the ordinary. She suggested that I put a collar on Oscar in order to prevent the plucking just for a month to allow the area in which she plucked to grow back. My husband and I decided that we did not want to collar the parrot for plucking since she would get extremely upset when she wore the collar.  Oscar is still doing the cry and lifting her left leg and she is still doing a bit of plucking in the area.

I am not totally concerned about the plucking, but I am concerned about the fact that it seems to be located in one general spot as well as she does the cry and then lift her left foot. It has been about two weeks since the Vet appointment and the plucking has not increase nor has it decrease. However, tonight after dinner I had her out and noticed that her left foot was dis-coloured, it was almost as if someone had taken a ruler and coloured in the three toes the same and the rest of the foot looked normal. It was kind of a light bulb moment, because I am pretty sure that I had seen this before, but at the time could not remember if this was her normal foot colouration. We went back to other photos that we have of her and the colouration is not there. The foot is not cold, but it kind of felt cool but then testing it again, I didn't.  If you have any ideas or suggestions, I would appreciate hearing them.

My suggestions and comments are general, in the absence of direct history collection and physical examination of the patient in question. In principle, you need to ask your veterinarian to complete a bit more of a database here. A baseline complete blood count and biochemistry profile make very good sense, to try to ascertain the general health status of your bird. I agree - the use of cervical or Elizabethan collars would not and probably should not be an early or first choice intervention for feather damaging behavior. If you feel that your bird is in pain, ask your veterinarian about analgesia or pain relief. The likelihood of feather lice or mites having a primary role in this problem are very very low. Furthermore, in such a young parrot, it would be prudent to seek marked and obvious behavioral causes as well as physical pain or other issues that could have a causative role here with your bird.