sewer odor

Hi everyone, I am having a serious issue with my newly remodeled guest house shower. See attached pic. Every day that I check by turning on the shower, sewer smell comes out from the new shower drain. It also happens when I flush the toilet first, before turning on the shower. The smell...

I have had a sewer gas smell coming from beneath my toilet for 2 months. Here is the info: -no leaks -toilet is one year old -new flange -new wax ring -all pipes in crawl and attic are tightly sealed and no obvious cracks or leaks -roof stacks checked -smell is intermittent -flange sits...