My youngest budgie, Kiwi (female, 5-6 months old) has just started bobbing her head, stretching her neck out with an open beak, and then wiping her beak on her perch. She repeats this again and again. It looks somewhat similar to crop adjustment, from a video I've seen.
When I examined her, there's no obstruction in her mouth (she bit me quite hard while holding her), but I did notice that her bottom of her beak has lost its top layers, exposing a darker layer where a dark blood vessel is visible below the surface. She's not bleeding. It looks like part of her beak flaked or chipped off.
Do you think she's making the regurgitating/crop adjustment motions out of discomfort from her beak? She's not regurgitating anything that I've seen. She doesn't seem ill. I just don't want to miss signs of something serious. Thank you.