Your drain is clogged. You really don’t want to use harsh chemicals, but your plunger isn’t doing the trick. Before you call the plumber try applying about 2 tablespoons of petroleum jelly (Vaseline) around the rim of the plunger. This will moisten the rubber edge helping it to stick to the bottom of your sink. This airtight closure will cause pressure to build up quickly and your clog should be eliminated in a jiffy.