Suddenly feeling dizzy may have the following diseases: First, hypertension, if a sudden and severe increase in blood pressure may cause dizziness and discomfort, which is caused by high blood pressure that increases intracranial pressure. Second, the presence of cerebrovascular disease, cerebrovascular disease, especially ischemic cerebrovascular disease, can cause dizziness in the sky if it affects parts of the body that control balance, such as the cerebellum. Third, diseases of the vestibular function of the inner ear, such as vertigo, may also cause sudden spinning dizziness that lasts for a long time. Fourth, cervical spondylosis may exist, and the compression of nerves by cervical spondylosis may also cause spinning dizziness.