Can someone help me with my eyes?

every once in a while for like two hours I get spots in front of my eyes. for example if I am reading I can only see about half of the letters in a word. its seems like things are just whited out or something. I have worn gles my whole life and have had this prroblem steadily for the past two years yet everytime I tell my eye doctor about it they say I am too young to have those types of problems with my eyes. what could this be? any ideas at all?