The first thing I'm going to tell you, is that you need to see a doctor and get to the bottom of this. People just don't pass out for no reason at all. It could be something serious, or something rather simple. But you don't know that, altho I'm sure you are guessing at it. I can think of a dozen reasons why this happened, but no sense in speculating. If it happens again you might not be so lucky! And since you live alone, you could lay there for a long time before being found.
Please - get yourself checked out thoroughly, even if you don't want to. You have those 2 beautiful girls to think about, and they need you. Don't just brush this off - PLEASE!!!!!