Actually a yeast infection is not in any way necessary. Vaginas do normally contain yeast but they also contain white blood cells (in addition to the good bacteria) which inhibit its growth. Plus, your vagina should be quite acidic, helping kill anything foreign.
In general, your vagina can take care of itself. Never, ever do anything that would mess with it! Wear panties that are a size or two too big, and always cotton. Better yet, wear none at all. Wear pants also made of cotton, and make sure the crotch of them does not touch your pussy, except when you are sitting down because then it's inevitable. Eat yogurt at least 5 times a week, and not the sweet, fancy ones, like Yoplait, because they are sweeter than candy (Hershy bar: 28 grams of sugar. Yoplait Nouriche: 42 grams!!). Instead, get a natural, organic, PLAIN yogurt like Brown Cow Farm, and sweeten it yourself with artificial sweetener and vanilla. Eat less that 80 grams of simple carbs (includes, sugar, and starch from corn, potatoes, and other high-glycemic foods) every day. 0 grams is better :P Unsweetened cranberry juice will burn a hole in your stomach, but you'll thank it anyway, because it will also treat the UTI. Also try blueberry juice. Don't douche! Don't use tampons! Nothing belongs in there but penises
And finally, never ever ever ignore a UTI even for an hour! Those nasty buggers will spread like a rumor and end up in your kidneys with less than 12 hours' delay. Go straight to your doctor and sit in the waiting room until he will see you just to make you go away.