I’m sorry you and your bird went through such an ordeal. It is quite possible that the drugs caused some type of physical or emotional damage. Feather destructive behavior can be caused just by a behavior issue, but more often it has a medical cause. It would be best to take her to a board certified Avian Vet who is familiar with the condition and knows what tests to run. There are a couple of viruses that they now suspect may cause feather destructive behavior, and sometimes it can be a skin allergy, infection, a nutritional issue or an allergy to a food. Allergies are very hard to determine in birds, but there are certain foods that can be suspect, as well as many artificial dyes or ingredients. She is really best off being seen by an Avian Vet to determine or rule out a medical cause. However, very often the bird still needs a collar until new feathers have grown in, because once they start plucking due to a medical reason, they can develop a habit and not be able to stop even when the health issue is resolved.
Thank you for asking Lafeber,