I Have Been Feeling Very Dizzy. It's Like The Room

I have been feeling very dizzy. It's like the room is spinning. If I move my head too suddenly it feels like my head is just so much pressure. I've gone too the hospital twice. One thinks it's the electricity of my heart. The other thinks I may have a thyroid problem. My mother just passed almost two months ago. I need help with getting rid of these dizzy spells and feelings nauseousnes. I can't really drive because it's affecting my vision. What should I do?