The previous responses to your question are right on the money. You could have a urinary tract infection, which needs to be attended to before it migrates up into your kidneys. You could also have a complicating yeast infection that would make the labia ourside your vagina so sore and swollen. Best go to your doctor or to an urgent care facility (depending on your insurance coverage) ASAP. Anything could be going on and you need to get on top of it.
It could be a urinary tract infection irritating the vagina or a vaginal infection irritating the urethra, the opening to the urinary tract. Definitely need to see your physician asap.
It sounds like a urinary tract infection. You should see your Dr for treatment. I hope you feel better soon. Take care. Remar