What Causes Sudden Unusual Behaviour And Dizziness?

My three-year-old grandson had a strange sensation this week. Suddenly crying out and climbing on a chair, he said the floor was moving, and later he described, as best he could, how the floor had started to fall and said that the whole house had begun to move. The episode lasted a few moments, but it was repeated the next day. He had been to the mountains the day before the first episode. Could it have anything to do with an imbalance in his inner ear or something like that?