Every night we come home to a smell which we imagine is a gas like smell in the porch and into the living room of our house.
We have disinfected the whole downstairs and used a capret cleaner on rugs etc. we have run taps in every place possible and put a hose down the gullies followed by zo flora and jeyes. It is driving us mad and we are concerned there could be implications for our toddler. Can anyone shed any light?

Natural gas. If there is a line into the house that goes under the porch, call the emergency number. It wouldn't hurt to call anyway.
Sewer gas. Locate the sewer line.
Dead mice or other animals. My parents' house is only 43 years old and reeks of dead mice and droppings and urine, in the walls and ceilings and floors, if I cut a tiny hole the blast is awful. (Discovered when renovating.)

Do you rent or own? Is there a basement? City, burbs, or rural?

Which gas smell: sewer gas, gasoline, natural gas, propane. Sure its gas an not mold or mildew?

Hey, no gas line into house &no basement, & a fast cat. CO monitor hasn't picked up any gas, but we turned off the bottled gas that fuels cooker (at the back of the house). Flushd drains at the same time. Smell is gone. Afraid to turn btl gas back on

The smell is gone for now. But we are afraid to turn the butane bottles back on that fuel the cooker. Does butane leak get picked up by your average household CO detector?
If so then we're still lost. We turned it back on today and we were sure we smelled it again by tonight. Maybe parnanoia though. Sewer drains have been hit hard with hoses and jeyes/zo flora.
Think we need to get everything checked one after the other by the sounds of it - nightmare. Thanks to all

Bottled butane or propane? Where do you live? CO detector would not pick up either. Whoever supplies you with bottled gas would have folks available to come out and check for a leak. No average homeowner would have a gas detector. Bottled gas leaks usually at connector, paint the connector with soapy water out at the bottle and everywhere there is a connector