I am sorry to hear that you are experiencing a yeast infection. They can be quite unpleasant, but fortunately they usually clear up quickly with an antifungal vaginal cream or oral antifungal medication.
Yeast infections are very common in women, and they generally result from an imbalance between the types of bacteria and yeast that live in the vagina.
For example, excessive cleaning of the vagina (with soap and water) or with douching products will definitely kill off the normal vaginal bacteria allowing the yeast to multiply and take over. Therefore, you should avoid this at all costs.
Change underwear daily is helpful, but it is also helpful to think about the type of underwear you use. They should be light, absorbent cotton underwear, as other types may predispose to infections.
Sometimes, yeast infections can be caused by sexual intercourse. This is because your partner may have yeast on their skin and may pass them to you during sex.
If this is your first yeast infection, then I would not worry
about this very much. Simply take the antifungal medications and it should clear up. If you start to have recurrent frequent yeast infections, then that is something to talk to your doctor