Don't assume it's a yeast infection. The truth is that if you are not immune compromised in any way, such as chemo treatment or AIDS or repeated Antibiotic usage, then it is not probable you have a yeast infection.
It is more likely a bacterial or pH imbalance. I find that a Vitamin C tablet inserted helps to restore the natural acidity of the vagina and kills unwanted bacteria while creating a rich environment for Lactobacillus (the good bacteria) to replenish.
Using an over the counter anti-fungal will only further intensify the problem, even if it is yeast the OTC stuff doesn't always work very well - Vitamin C does the trick with no side effects or super messy cream.