Could my moisturizer have caused a yeast infection?

Many of the intravaginal moisturizers (like the Lubrigyn you mention) will correct or “normalize” the vaginal pH. (An atrophic vagina has a more “basic” pH, and a healthy vagina is more acidic.) Use of a moisturizer will cause a transition of the pH to a more health status, which is a shift of bacteria; you’ll end up with more lactobacilli, which is a good thing.

But whenever we make a shift, the time of transition is a bit of risk for a yeast infection. This is not an adverse effect of the product, but more likely indicates that it is making a difference. Go ahead and treat the yeast infection, and I’d recommend continued use of Lubrigyn. This shouldn’t be a recurrent event once tissues are healthier.