Suggest Remedy For White Blindness With Dizziness

Often times while casually walking anywhere I ll experience a white blindness and dizziness. It comes about in a sudden moment, slightly gradually until it s completely white. It s sort of the feeling you get when you re about to faint but not quite. The blindess blocks out all my vision, but I can still hear. At the same time my fingers begin to tingle and i lose sudden control of my body, like my knees begin to wobble. I realize I slightly shake during this too. It only lasts 4-15 seconds, I can just keep walking after it s done. I am 15, 5 8-5 9 and weigh 127 lbs. What can possibly be wrong...should i see a doctor. Perhaps im just dehydrated?