I have never done IV antibiotics, so I can't speak to that.
But, in addition to what antibiotics do to your gut flora (thus clearing the way for yeast), yeast will feed on bacterial die-off and vaginal yeast infections actually start as yeast overgrowth in the gut, so that's my first line of defense. Here is something I wrote in an email recently:
Twice, I have eaten an anti-yeast diet for several months:
Organic yogurt twice a day (I typically eat Yo-Baby from Stonyfield Farms).
Avoid sugars and carbs.
Avoid things that contain or promote yeast, like yeast breads, pizza, cheese, pickles (and sugars and carbs).
Eat lettuce every day or at least 4 days a week.
Have lots of grilled or baked meats and raw or lightly cooked veggies.
In addition to the anti-yeast diet, the following supplements have helped my gut:
sea salt, coconut oil, glyconutrients, aloe vera, gelatin (pour a packet in hot water and add a little fruit juice for flavor, stir vigorously and drink while still fairly warm) and any nutrients I happened to be deficient in at any particular time.
I have also found that anti-fungal herbs, like oil of oregano, can help combat yeast overgrowth.
Good luck with this.