I had a plumber come out and install vents on all my drains but still have the fumes coming into my house.

still have the fumes coming into my house. These fumes are from outside? How do they get into your house if the house is closed up. Is there a vent on the septic tank? I'm trying to understand your problem but I haven't enough details to go on. Can you furnish more details? Back to you. Tom

Are you telling us you have a home that did not have a vent stack on any drain lines? Where do you live?

Yes I had some but not all. Originally did not have gray water going into septic tank. I live in the south.

The septic tank is concrete and no it does not have a vent pipe on it.

Was there a trap or fixture that was left unvented? Is there a basement floor drain
? What state at in the South? Do you know what plumbing code you fall under? Back to you, Tom