Has the vet ran any tests to determine the cause of the mutilation?
She had a checkup when I got her and that was just a basic physical, and this time it was just cleaning her wounds so no
Monica makes an extremely good point...If your vet is not a Certified Avian Vet (maybe an "exotics" vet), or if they are a CAV but they have no self-mutilation/feather-destructive behavior experience, then you really do need to find a CAV who is very experienced in diagnosing and treating them, as there is often times a physical problem that is causing the mutilation and/or plucking...And sometimes the physical problem is caused by an environmental issue, a food issue, etc., or in other words an "allergy"...Most CAV's with experience in this field who are seeing a bird who is self-mutilating for the first time will make taking blood their number one priority, as sometimes a routine blood-panel will tell them exactly what is going on; and if the routine blood-panel doesn't give them a diagnosis, then that's when the difference between an experienced CAV and other vets really makes a huge difference, as they know exactly what specific, individual blood tests also need to be run in addition to the routine CBC, metabolic panels, etc. They typically run tests for allergies (antibody tests), and then some very specific metabolic blood tests to test for any type of food-allergies. They also usually pluck some feathers and do skin-scrapings to do microscopy and even cytology on. And if all of this comes back as being normal, that's when they start looking into both possible environmental issues as well as the psychological issues, such as anxiety...
If you have a lovebird that also plucks then you really would benefit from finding a CAV who specializes in self-mutilation. And if your lovebird plucks his chest/belly then yes, definitely try a sweater for him, as every single bird I've seen wearing a sweater has had great success with them. They definitely accept them much more easily than the cones/collars, and they protect the damaged areas so well that their feathers in those areas are able to grow-back very quickly, and in a lot of cases once the feathers are completely grown back-in and we end-up re=homing the bird to a great home where they are getting a lot of attention, love, a good diet, mental stimulation, etc., then they stop plucking completely....