The causes of dizziness according to the decreasing incidence are:
1) Benign paroxysmal positional vertigo (BPPV) 20%
2) Vestibular 15%
3) Migraine and motion sensitivity 15%
4) Anxiety and depression 10%
5) Meniere's disease 7%
6) Cerebellar disease 6%
7) Transient ischemic attacks 5%
8) Orthostatic hypotension 4%
Your primary care physician should refer you to a neurologist, cardiologist and ENT specialist for evaluation as the causes can be divided on the system, which is involved:
1) Inner ear or internal ear disease
2) Central nervous system
3) Cardiovascular, or
4) Systemic diseases
Internal ear disease vertigo is termed true vertigo in which one feels rotational movement of self or the surroundings. The false vertigo or nonvertigo has feeling of light-headedness, unsteadiness, motion intolerance, imbalance, etc. You need to consult first an ENT specialist to rule out the diseases of internal ear. They will perform some clinical tests (vestibular diagnostic tests) to establish the cause. Often, dizziness can be a multisensory disorder due to any combination of peripheral neuropathy, visual impairment, and musculoskeletal disease. Not properly controlled thyroid dysfunction can present with dizziness as an initial complaint. In individuals who have migraine; dizziness and vertigo can occur as part of the aura or separately. Spells usually last approximately an hour but can last several hours or days in patients who have severe symptoms. Most patients who have migraines have a long history of recurring symptoms. So that too should be assessed as a cause if you have a history of migraine. Sometimes MRI of the brain and neck spine is needed for assessment.
Please feel free for your follow up questions.