How long does a yeast infection take to leave naturally?

So I think I just got a yeast infection. My discharge is a little bit lumpy and downstairs is kinda itchy and it kinda hurts. So, how long will it take to go away naturally? Or do I absolutely need medication for it? Is there a cream for it or pills or something? It's awkward for me.. I'm in middle school, and I don't really know what to do.  It's really bugging me, and I want it to leave. Thanks!