My daughter is 17 years old, 5'4", 125 pounds, very athletic. Over the past couple of months, she has intermittently complained of a sudden onset dizziness behind her eyes that persists for a few minutes and then goes away. Sometimes it happens once in a day, other times it happens several times a day. She had last complained about a month ago, and then had several episodes last night. There are no other symptoms. No nausea, vomiting, headaches, etc. It just scares her because it comes out of nowhere and apparently is pretty intense. Any thoughts?