Y DO I FEEL LIKE IM OUT OF BREATH?

DIZ DOESNT HAPPEN OFTEN BT LATELY IVE BEN FEELIN OUT OF BREATH ALOT WHILE IM SITTIN OR LAYIN DOWN.SUMTIMES I WAKE UP AND MOMENTS LATER I FEEL LIKE DAT..IT DIDNT HAPPEN DIZ MUCH.IVE FELT LIKE DIZ FOR YEARZ BT ITZ WORSE DIZ TIME.IT BOTHERS ME BCUZ ITZ LIKE IM GTIN WEEK OR LIGHT HEADED..ITZ HARD 2 EXPLAIN THO..Y DO I FEEL LIKE DIZ??