I think you are suffering from BPPV.
BPPV (benign paroxysmal positional vertigo) is one of the most common causes of
peripheral vertigo (vertigo not associated with the brain and
spinal cord).
As its names suggest, the vertigo tends to occur with certain positions. The positions can vary during the course of the illness and may also vary from one person to the next with this condition.
The loss of balance when you are looking down and when your head is at certain angles is related to the BPPV.
The other common causes of peripheral vertigo are menieres and
vestibular neuronitis but these are a little different than the BPPV. In menieres, there is usually
hearing loss and
tinnitus.
IN vestibular neuronitis, the episodes of vertigo lasts for hours at a time.
BPPV is normally treated with certain maneuvers that you probably had at your doctor's office, the epley or semont maneuvers.
Despite these , it can sometimes still last for a long period of time in some persons.
ALSO ,you may try taking tab vertipress twice daily for relief.