Suzie-Q wrote:
Lately I've begun to smell sewage in one of my bathrooms. Of course

First make sure noone in your house is going to the bathroom right
before you. That could cause a sewage smell in the bathroom.

If not that, it has to be some kind of back flow from the sewer. Is
your toilet trap staying full of water? A vacuum in the sewer system
can suck the water out and make stinkies. Same for the sink.