What Causes Vaginal Itching And Redness On Labia?

i am having extreme itching inside my vaginal cavity. my clitoris and labia are both swollen and red, and have been like this for over 48hrs. i have drank 2 liters of water today and have only urinated twice, but even then, not much urine was excreted. there is burning during urination, urine is yellow, and discharge is yellow with a medium thick consistency. what could this be? (27yr old female, 189lbs, not pregnant)