What Causes Head Spinning, Dizziness With Loss Of Balance?

One day , i woke up in the morning and having terrible spinning head. That day, i observed, when i was lying down on my bed in straight upright position with face towards ceiling, i was feeling spinning head. I went to physician and from next day, there is no spinning head. But i am feeling dizziness. Sometimes feel a little off balance. What could be the reason.