Yep go to the doc. Anytime there is a foul smell, infection is suspect. Your discharge should have a faint smell to it, but if you can smell it even when you're not trying to, (like naked and standing up) that's a problem.
And the itching is just another thing that makes me think of an infection. Go to the doc. It could be a yeast infection, could be a bacterial infection, but either way, it needs to get treated. You don't want these things to stick around.