Lisa, when you had your line rootered out did they go through the trap of the drain or the clean-out on the inside of the drain? Have you checked to see if there is an opening on the side of the drain, located inside the drain bowl itself? The clean out plug for the drain may not have been re-installed after having your line augered. This would allow a direct flow of sewer gas to the atmosphere in your basement. As far as your low water pressure is concerned you haven’t given enough information as to what work you had performed to allow even an educated guess as to what might be causing this problem.