Is it back and forth or up and down?
Is she white?
Do her eyes do that as well? (Get close and look at them-again same question if they are-is it up and down or left to right?)
A couple of things come to mind.
One is many rabbits with compromised vision (not blind) often red eyed white-do an up and down motion. It seems to be them trying to see better. That one is quite common.
The other thing that comes to mind is an intentional tremor (we are actually sorting that out in my bun right now) -he goes from left to right left to right-almost looks like he’s reading.
An intentional tremor can have many causes or be idiopathic (no cause) and the way it works is:
Say you have an intentional tremor in your hand. When you are sitting and doing nothing-there is no tremor. But when you grab for a doorknob there is a tremor-so it’s only when doing something.
So for my bun, what we are thinking is that it’s when he is moving his head *intentionally* the tremor kicks in.
But I’m going on and on. It very much depends on if it’s up and down or left to right, as well as if the eyes are also moving; and probably the best thing to do is see a good vet soon.