i tagged a few members that have bullies with the extreme end of this issue, but it could also be something as simple as an itch she can not reach. have you checked the tail pocket and cleaned it ? Check the belly see it it need a wipe down.
My boy did the air licking out of being board and somewhat OCD.
can you get video and post it for us to see what she is doing?
My Boeboe did that a lot before she had her Entropion surgery (Eyelashes scratching the eye). She sat and kind of looked at the roof and licked her nose repeatedly. She could sit like that forever if I didn't distract her. But like everyone says, it can be many reasons for this behavior.
Our vet called it "fly biting." Our Leiah did that occasionally beginning about 2 years old. It can be neurological, so really does need to be checked out. Leiah's situation never worsened until about a month before she passed at 12 years old. At that time she developed a seizure disorder, but she lived a good life till then. Please let us know how this goes.