Oh do I understand the stuck and pissed, and $$$ stressed and tired.
If you want to talk over what you've already done and seen, and brainstorm, give me a call. I'm not an environmental hygienist, but I've unfortunately dealt with hidden sources. And as the CIH I work with repeatedly told me, "an outlet or hairline crack in the drywall is like a highway" and the killer thing is that "every time you change air pressure, say by closing a door, it forces mold fragments & mycotoxins out through those gaps".
So if I can help with the detective work, I will.
Where are you located?
Lucy
PS. I'm a night owl on PST, in the SF Bay Area. Send a DM.