You really need to use probiotics - I liked kefir the best as it has a lot more good strains of bacteria and healthy yeasts than you can get through pills.
If you choose to use the pills though, be sure that you get the ones that require refrigeration and have the highest number of good strains of bacteria - it's quite literally, the more - the merrier (your tummy will be!).
The yeast is due to the abx - they kill off the good bacteria in the mouth & gut along with the bad - but the bad yeast will grow much quicker and will be the one to replenish the mouth and gut if not held in check with a good probiotic. You will need to take at least 10,000 units a day - some people find that they need to take 50,000 a day.
You should avoid some foods as well. I like this article for making sense of it all:
altmedicine.about.com/od/popularhealthdiets/a/candidadiet.htm