I agree that it's best to go see your doctor/gyna about this especially if you've never had a vaginal infection or experienced anything like this before. It may or may not be a yeast infection, you won't know until an exam is done.
I don't try to "self-diagnose" any kind of vaginal infections or problems anymore. If I know something is wrong, I always see a doctor. Cause there have been times where I thought I had an infection but it ended up being nothing after my doctor did the exam. Other times it ended up being bacterial vaginosis rather than yeast when I did have an infection:
http://en.wikipedia.org/wiki/Bacterial_vaginosis
Now don't let the site scare you! You can get both infections without even having sex at all. You could of been taking antibiotics and gotten it, or from even shaving down there! Shaving makes the area more vulnerable to bacteria.
But I really hope you decide to see a doctor for this instead of trying any over the counter treatments for a yeast infection. Although Monistat (I think?) makes a vaginal infection screening test you can buy OTC that can help you know if there is anything wrong that may need treatment from a doctor.