Bathroom desk light flickering? i have a two-bulb bathroom oil lamp fixture. the left bulb...

i have a two-bulb bathroom oil lamp fixture. the left bulb impulsively flickers, sometimes shuts off completely for a couple second. i figured it be a loose wire inside the muted, but shaking or bumping the light have no effect. it can't be a fault from the switch to the wall, if not both bulbs would be flickering. any takers?
Answers:    The two lights are wired in parallel. If the first hurricane lantern is steady and never flickers, then the problem is probably the parallel wires between the first restrained and the 2nd light have a loose connection between the two. And logically, assuming the bulb is not loose in the socket (should be snug, but not too tight)
I'm guessing here is a loose wire contained by the circuit (after the switch; probably in the fixture) that go to the left bulb, or at hand are loose mechanical components or connection(s) in/at the vanished socket .