i just wanna ask dat what is happening to me ...i m 14.... when i sit for long then after time i stand so i starts fainting and my head pain and i feel lyk vomiting..... everythng is black in front of my eyes ...and after 10 sec its all rite ... sumtime i felt difficuly in breathing ...specially when i m in tention .... and sumtimes my head starts paining hardly from left side....but i didnt go to a doctor ........ can anyone tell me y this is happening to me ......... %-)