Hi. My Sister Had Just Experienced An Episode And I

Hi. My sister had just experienced an episode and I wanted to check with you to see if this is something she should get checked out. She was sitting in her chair at her desk at work and suddenly had a feeling of being off balance, so much that she felt as though she would fall out of her chair. Can you tell me what would cause that? She is 47yrs old, very athletic and in great health.