Have You Ever Fainted? What Caused It?

I woke up at around 4 in the morning today because I had horrible stomach pain. I went into the bathroom where I began feeling dizzy, there was ringing in my ears, and I was sweating like never before, I also lost all color in my face. The next thing I know, I woke up on the floor of my bathroom, I don't know how long I was out. Obviously I have to go to the doctor, but I'm curious to see if this has ever happened to any of you? If so, what caused you to faint?
Have You Ever Fainted? What Caused It?
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