A nurse here: go see your MD.
Before you go, make a list of what has been happening, when it has been happening, whether or not you ate, how you have been resting and sleeping, any aches or pains anywhere in your body (headache? chest? fluttery feelings?) and even try to think of *anything* abnormal or out of the ordinary that you may be experiencing whether you think it relates to these episodes or not. This could be something as easy to fix as hypoglycemia (low blood sugar), but could be something more serious. Only way to know is to get yourself checked out. Passing out and coming to on the floor is NOT normal.
Take Care & let us know....
Julie