Sounds strange to me. Before you rush out and buy a new switch double check that the same fuse isnt blown again. All those things run on the same fuse. If there is a short somewhere it will continue to blow the fuse. The reason your brake lights work is because they aren't on the same circuit.
If your LH light was out, im assuming parker light, why would only one of them be out if the fuse was blown? The whole circuit would have failed, therefore all of lights on the same circuit wouldnt be working.
Then again it could be the switch.. You could test it for continuity.