I had pretty bad dizziness right after the concussion and then it subsided. Would come on again now and then but nothing sustained. A few weeks ago I had a pretty bad episode that lasted for about a week.

I'd be walking somewhere and suddenly have to stop. It coincided with the sound in my left ear going muffly. Then, one night I laid down in bed and closed my eyes, and suddenly I felt like I was on an amusement park ride being thrown large distances through the air. Totally crazy.

My doctor felt that it was labyrinthitis http://en.wikipedia.org/wiki/Labyrinthitis