since the age of 11 I have been experiencing spells that include all of the following symptoms. I feel it coming on.. start feeling dizzy , my vision gradually goes to black, i cannot see anything, all I can hear is ringing/buzzing in my ears... I feel warm... I have no balance and my legs/knees go weak to where i cannot hold myself up.. These spells last anywhere from 2 - 5 minutes ... Afterward I feel exhausted , my legs hurt very badly ... I have mentioned this to my current physician.. tests have been done .. nobody has been able to find and explanation ... please help me ..