I’ve had this same problem for years; it runs in my family. I black out all the time when I stand up. My mom would always eat black licorice, because she remembers reading that it helped increase blood pressure. I don’t know where she got that information and haven’t bothered looking, but maybe there’s an ingredient found in black licorice that might help. Obviously the sugar wouldn’t help your candida problem.
I find that drinking plenty of water throughout the day helps a lot.