New plumbing and dishwasher installed by kitchen renovation subcontractor plumber. The dishwasher and sinks developed a smell like rotting food. I called plumber a couple of days ago to come back and am waiting. I am just wondering if this can be fixed without dropping the drain pipe in the wall. I know the p trap is too deep at 4 1/4 inches. Also the trap water backs up into the horizontal pipe to the non disposal sink.