Sulfur/sewage-type smell coming from sink drain -- what's the problem, and how do I fix it?

Rather curiously, it's only from one sink in my house; the other drains are fine. No amount of drain cleaner and boiling water have done anything... It's the bathroom sink, sadly. (It's a bit nauseating to brush my teeth these days.) Am off to try vinegar & baking soda... Thanks!