What brain diseases can cause dizziness and it being only symptom?

The inner ear.: Dizziness is a difficult term. Most people mean the room is spinning around them when 'dizzy'. Moving usually makes it worse. If that is what you are feeling, you likely have an inner ear disorder such as labyrinthitis or BPPV Benign Paroxysmal Positional Vertigo, if there are no other symptoms. Meniere's is another but usually has tinnitis & hearing loss with the episodes. See an ENT doctor

Brain&Sinus CT CLEAR: Dizziness can be caused by a variety of things, from inner ear canal issues, to afferentation, or improper perception of incoming nerve signals. It may be appropriate to review medications, have inner ears evaluated, and see a Doctor of Chiropractic focusing on dizziness review epley's maneuver, and vestibular rehabilitation exercises to determine if beneficial. Overuse of stimulants can effect.