We finally found the problem after 5 months of sewer smell in my house. A wonderful and caring carpenter helped me with this. The whole entire plumbing from my sink down to the cleanout in my rec room had to be replaced. The shoddy workmanship by the plumber was unbelievable. No glue on some pipes, pipes not angled properly, all led to gases escaping. My kitchen cupboards had to be cut along with the wall in my rec room to access all of these pipes, but at least now I have no more sewer smell. Thanks Brian!!