There are so many reasons why your vagina could be itchy or producing weird discharge in your underwear , and if it is because of a yeast infection, then it's usually pretty easy to treat. But you should probably see your gynecologist (the internet is not a doctor ), or at least call them to tell them you think you have one, because there's a small chance the symptoms could be indicative of a more serious medical condition, like an STI or even diabetes. Your doctor can do a quick swab of your vagina and let you know exactly what it is you're dealing with. Ahead, a few basics to know about yeast infections.