There are services that show up with a cute little beagle and they can tell you if you have mold in the walls without tearing them out.
I’m not sure that solves your problem though.
Shellac is the world champ for sealing in odors. You could put down a coat of SealCoat (clear) or Bin (pigmented) shellac. It won’t get rid of the smell, but it will seal it in.
But before I sealed in the smell, I would want that cute beagle to tell me if I had black mold in the house.
Unlike asbestos, which you can live with in your house as long as you don’t disturb it, black mold is out to get you.