There are many reasons why you might be experiencing the feeling of passing out regularly. Some of the reasons are extreme fatigue, blood loss, and extreme heat, staying in crowded places, irregular cardiac rate or even pregnancy. You should visit a physician to get proper screening and treatment.
Maybe your sleepy or a bit dizzy, get some rest and see if it works and eat something light so you can rest better if it doesn't work contact a doctor, this sort of thing happens to me and i just eat something light and go to sleep it works for me. hope ya get better.