Why does my car smell like gasoline?

I had my car oil and filter changed last weekend and I started to notice my car has been smelling like gasoline. The car has been driven all week long and the gas levels have not changed abnormally.
I would smell it extra strong when I would put the air on but that is no longer the case. Now it only smells if I put the air on to circulate the air inside. I still smell it when I stand next to the car on the drivers side mostly. I don’t smell it in the engine.
I’ve checked under the car in the morning to see if there may be a gas leak but I don’t see anything.
Has anyone ever had this problem before?
Oh, one more thing. It is also giving me problems starting up. Before the oil change, my car would start up no problems. My car is a standard.