What Causes Fainting Spells With Breathing Difficulty?

doctors but they r unable to find diagnosis have history of faint,air obstruction problem,all says i should concert cycastris, h/o microcytic hypochromic anemia.wat to do im unable to study because of my health .i become uncosious for small duration when i back in concious state i start coughing and unable to breath,this is from last 2 years,doctors give aveil & decadon injection& oxygen therapy at that time,plz give me diagnosis