My chihuahua constantly licks the air and bites at the air. It looks like she is biting at bugs in the air, but there is nothing there. She is obsessed with doing this. Is this some type of ocb? What can I do to help her?

Why is often speculative. If she is less than 3 years old, she might enjoy a chance to play with other dogs and bite, bite, bite. If she is a young puppy, avoid exposing her to any but known well cared for dogs up to date on their shots.
http://www.photolocker.net/images/Labman/gretchenandellaplaying.jpg

My dog does this when he has hair stuck in his mouth and is trying to get it out.