Thanks for your question. It sounds like your parakeet has 2 separate problems. One is the sneezing, the other is feather destructive behavior.
The first step in diagnosing and correcting these problems is a thorough physical exam by an experienced avian veterinarian. The sneezing may be related to sinus infections, environmental changes, or other reasons. Feather destructive behavior is a complex behavioral problem and can be challenging to manage.
Please make an appointment with Dr Helmer, our Board-Certified Avian Specialist at your earliest convenience so we can help your parakeet feel better. 813 885 4477