The major root cause is antibiotics or anything that is anti-bacterial and causes bacteria to be eliminated and candida will take over. The majority of your immune system is good bacteria and then white blood cells. Our gut flora outnumbers our white blood cells 10:1. So when people say immune system they need to refer to their gut flora and white blood cells. People can have the most efficient white blood cells there are, but if fungal candida dominates the gut the white blood cells don’t stand a chance.
Acidosis contributes to inflammation more than anything. The vagina has a PH of 3.5-4.5, which is a pretty acidic condition. If the PH gets higher its more prone to yeast infections. Fungal candida does better in alkaline conditions. Our good bacteria secretes beneficial “acids”( acetic acids, propionic acid, butyric acid etc….): to keep candida from going fungal. Society consumes the wrong “type” of acids or acid forming chemicals/substances. If acidosis was a major contributor to candida then a lot more of America would have more “severe” candida. I know too many people that have a crappy diet that don’t have candida overgrowth. But as soon as you put them on a long round of antibiotics their health can change very quickly.
Having the stomach flu should not be enough to eliminate your good bacteria in your gut and cause a major candida condition. Our gut flora is mainly what keeps candida under “control”. Our white blood cells keep it in “check”. White blood cells are more suited for mild yeast overgrowths. So unless you took a long round of antibiotics you should be able to recover pretty quickly.