How to get rid of sewer gas smell after having drains snaked.

This diy site might help. Pretty easy ingredients and people say it works. Hope that helps.

https://dengarden.com/home-improvement/Phew-Whats-that-awful-smell-Could-it-be-sewer-gas-invading-your-home

It comes from the drains being opened again. Pour water down them. If the drains aren't used very much you have to put water down them occasionally to keep water in them to prevent the sewer gas smell from showing up. My mom had a couple in the basement she had to do that to because they never had water going down it.

Every drain in your house has (or should have) a P-trap — a U-shaped piece of pipe that holds a small amount of water at all times. The water serves as a plug to keep sewer gas from rising up the drain (toilets have their own internal version of a trap). This simple system works beautifully unless one of the following happens:

The plumber failed to install a trap or installed it improperly, in which case you’d probably smell gas all the time.

The drain isn’t properly vented, and a suction effect in the system siphons the trap dry. The same thing can happen if the vent is blocked (from tree leaves, bird nests, snow, etc.). The snaking may have blocked the vent causing a siphoning effect sucking water out of the P-traps.

The fixture served by the drain is too close to other fixtures, such as a toilet drain that’s too close to a sink drain; the force of the toilet flush can siphon the sink trap dry.

If you suspect a dry trap, run water in the fixture slowly for a few minutes, then shut it off and do a smell test. This should fill the trap and stop the sewer smell. Check to make sure the drains hold water. Check that the vent pipes are not clogged.

If this one doesn't help, it might be time to go to a plumbing outfit, and describe the problem. I sure hope you don't need one, but sometimes they are worth their weight in gold.

http://homeguides.sfgate.com/stop-sewer-gas-entering-house-38627.html