It sounds like you have a yeast infection. Usually if it is smelly then that is the case. I have had many in my time.
It could either be a yeast infection or a bladder infection. If you are sexually active it could also be an STD. The best thing to do is go to a doctor and have it checked out. But if that isn't possible, there is a kit in the store that detects various infections that a female might have. See what that result is, and go from there. If it begins to burn or persists for more than a week, your best bet is to go to a doctor.