Any recommendations on a good electrician/ contractor/ handyman who might be able to do a comprehensive diagnosis, rather than a whack-a-mole, fix this-then-that approach?

No self-respecting doctor diagnosis mental illness over the phone in 30 minutes and the time it takes to swipe a credit card..

 @JD Martin hit the points spot on @Young Kim with his diagnosis of old constructions (conventional construction) verse new construction (new come about in the early 70's).

If AHS is unable to diagnose whether a Covered Item malfunction exists due to an existing code violation, this code violation coverage shall not apply, and you are responsible for correcting the existing code violation in order to allow AHS to conduct such diagnosis."

Some states value emotional support animals as necessities, while others have levels to their need, a lot of it goes alongside the person's diagnosis which you cannot ask for.My advice would be to brush up on your state's laws regarding emotional support animals, and seek legal advice on the matter if its that big of a deal. 

So look for a GOOD Tech....Just a story for you: I had (3) certified A/C service techs standing around talking to each other for 45 minutes about why an A/C unit would not cool to 70 inside in 103 degree heat outside when it previously had no trouble do so.They put gauges on it, and a multi-meter and could only GUESS the Refrigerant was low.They made all kinds of statements that alerted me they didn't know what they were doing (picture the three stooges here).I dismissed them, because in talking with them I quickly figured out they knew little about A/C diagnosis, despite being certified.As in school, you have A students, B students, C students and D students. 

Especially now that the diagnosis has come into play....and more importantly the fact that you know about it.

They will need to obtain a doctor's diagnosis that she is incapacitated.

Not that being a realtor guarantees you are more ethical, but there you are trained and there is a governing body watching realtors.As far as the right choice for you, please don't think that your ADD diagnosis should hold you back.

But enter a cancer diagnosis or a major accident and when you're in bankruptcy court, I'm guessing you'll be singing a different tune.That said, health care coops are becoming more popular for people who fall outside of employer coverage and you might see if your local chamber of commerce or small business owners group has a coop so that you can get group rates.