Mathf.SmoothDamp freeking out?

I am trying to lag the player body behind the player head, but when my character falls down, or the rotation in the x or z changes at all things just spaz and freek out. That is about all the detail that I can give because I don't know what is causing it. Here is the relevant code:

 horizontalRot += Input.GetAxis ("Mouse X") * mouseSensitivity;
         currentYRot = Mathf.SmoothDamp(currentYRot, horizontalRot, ref yRotV, smoothDamp);
 
         transform.localRotation = Quaternion.Euler(transform.localEulerAngles.x, currentYRot, transform.localEulerAngles.z);

Any advice would be helpful, thanks!