However, look her over very carefully for mites and lice, just to make sure.
Mites live on the perches, not the animal so you are looking for dark freckles on the skin where they have been biting, or eaten areas on the feathers.
Lice live on the bird and can be seen but are very small. They like hanging out by the vent and under the wings and leave crusty looking egg cases at the bases of feathers.
Have you checked them over real well for mites and/or lice?
Google images of lice/mites and their eggs before the inspection so you'll know what you're looking for.
Part the feathers right down to the skin around vent, head/neck and under wings.
Best done well after dark with a strong flashlight/headlight, easier to 'catch' bird and also to check for the mites that live in structure and only come out at night to feed off roosting birds.
Wipe a white paper towel along the underside of roost to look for red smears(smashed well fed mites).