96' Saturn SL2

I have a 96 saturn sl2. About 3 weeks ago i was driving to town and started hearing a noise, sounded like was comming from driver front side wheel, got real bad so took it to mechanics shop, he drove it and noise stopped. But it would make humming noise in 2nd gear and jerks in reverse and no power in reverse, mechanic said was transmission, but it still shifts smooth and been driving it since then and doesnt seem get worse. Do you think its the transmission or could it be something else like CV shaft, vaccum leak or anything?