I have a sewer smell coming when shower is on in second bath. Only smells when shower is used.
Not the water heater because doesn't smell anyplace else. Not at all apparent that it is coming from the drain. It doesn't always smell. When it does - its bad and it lingers.
Had a smoke test found a leak closed it, but, it's still smelling.
Any ideas? 4 plumbers no remedies! I am at my wit's end!

Robin,
Are you certain the odor is coming from the shower, and if so, what kind of shower base do you have. Tiled shower floors, that do not have a properly pitched liner pan, can be the source of odors...