You can start googling the possibilities. Hopefully it is just Benign Paroxysmal Positional Vertigo (Bppv) which is mostly fixable.
Causes of Dizziness:
Dizziness can be grouped into types by the portion of the entire balance system that is not working properly. The different portions include the inner ear, the brain, the eyes, and the limbs, neck, back, and leg muscles and joints, which react to keep us upright.
Inner Ear Dizziness:
Half of the inner ear is used for hearing, the cochlea. The other half is used for balance, the labyrinth. If the labyrinth, with the nerve that connects it to the brain, is malfunctioning, dizziness can result. Many types of maladies occur in the inner ear to cause dizziness including Meniere's disease, labyrinthitis, positional vertigo, and vestibular neuritis, vestibular migraine, and tumors of the inner ear nerves. These usually cause imbalance, vertigo, and nausea. It can also be accompanied by tinnitus and hearing loss, if the nearby cochlea is also affected.
Central Dizziness:
Central dizziness is caused by problems in the balance portion of the brain. Any time this portion of the brain is not working properly, dizziness can occur. Symptoms usually include lightheadedness, disorientation, imbalance, and sometimes even blacking out. Causes of central dizziness include low blood sugar, low blood pressure to the brain, strokes, multiple sclerosis, migraine, head injury, tumors, and the aging process, among others. Treating these types of dizziness usually involves treating the problem that is causing the brain not to work properly.