We have a smell that only comes from the kitchen sink sometimes.
I have tried cleaning it all different ways many times. Have taken the plumbing apart by the Ptrap and have done the baking soda thing all different ways.
We put in a new dishwasher a few months back and the smell subsided. It is now back but only sometimes from the sink, which makes it go to dishwasher also. When dishwasher was installed the guys were told of the problem so I am sure my plumbing is right.
I also had a friend look at it and he told me it looked good. He is a plumber.
Can it be something behind the walls that I would have no clue about?

