Just encountered this. After exiting combat in VATS I could no longer move the camera up or down in first person mode, only left or right. I tried entering/exiting VATS again, fast traveling, entering/exiting build mode, crouching, sprinting, nothing worked. Even reloading the save I made after I got the bug didn't work.
This is nasty. If you don't have a previous save to reload you are pretty much screwed.