I have the same thing happen, it can be frustrating understanding why it happens & when. I constantly feel angry towards having vasovagal syncope. My family & especially my boyfriends family has a hard time understanding what it’s like. Doctors never have a clue either on what they can do for it. I personally feel one come on if it’s too hot, I’m standing for a long period of time, not eating, or I’ve injured myself. Feel free to message! :)