Hello, thanks for asking in Healthcare Magic. Neck stiffness, nausea and dizziness on head movements, vertigo (spinning of room) and light headedness (un balanced head) are all suggestive of either BPPV (Benign Paroxismal Positional Vertigo) or Cervical Spondylosis. Sudden violent movement of head results in severe dizziness. You are comfortable in your treadmill prabably because your head movements are minimal during treadmill. Loss of hearing can occur due to BPPV but not due to cervical spondylosis. BPPV occurs due to problems in inner ear. Change in position like rolling in bed results in spinning sensation due to changes in head position. Nausea will be much more severe in BPPV than in cervical spondylosis. Although loss of balance occurs in BPPV, neck stiffness is rare. MRI and CT scan of head can help in diagnosis. Labyrinthine sedatives like Diazepam or anti histamines like Meclizine may help. As we grow older, the bones undergo degenerative changes due to wear and tear reducing the space of the spinal column or the space where the spinal nerve exits. This compresses the nerves and blood vessels passing through that opening. In your case, since the arteries (blood vessels) are constricted (narrowed) you feel severe dizziness as it reduces the blood supply to the brain. MRI and X-Ray of neck (cervial region) will confirm the diagnosis in cervical spodylosis. Treatment aims at restricting the head movements by cervical collar, mild physiotherapy to strengthen the muscles (exercises should not be done if your dizziness is severe) and drugs like Vertin (Beta histine) which can improve the blood supply. I hope this is helpful to you.