I would absolutely take her to the vet. No question about it. It may be heart burn. Have you tried giving her Prilosec? I forget the dosage. Ask your vet if you can try it. When Toker, my son's dog has had episodes of obsessive licking, she licks things though, not just the air. She licks the hard floor, carpeted floor and the air. I asked the vet about it and that's what he suggested. So, I gave her Prilosec and it stopped. It's happened on a few occasions, but not very often.
How long has this been going on? Can you notice any pattern...like what was she doing right before or a half hour before? Anyhow, it is not normal. She should be checked out by a vet. Hope something will be discovered and fixed.
If it's behavioral, is she getting plenty of stimulation and things to do? You mention being harsh with her to get her to stop. Dobermans are typically very, very sensitive psychologically and don't usually do well with any harshness. Of course, I don't really know what you mean. If she's getting a lot of reaction when she's doing this, it is possible to escalate it. If you can distract her, call her to go outside with you to play, does that help?
Well, anything is possible...there are many types of seizures and some are not very obvious at all. Teeth could possibly be bugging her. Heartburn, some sore in her mouth or on the roof of it. But it doesn't look very pleasant for her, so hopefully a vet can figure something out. Good luck.