Underlying adhd behaviors is an interesting diagnosis. Doesn't sound like they are very sure of themselves. Which is ok. There are many things that can look like ADHD. What kind of a doctor did you see?
Diet is always worth checking out. I have even seen cases where lack of sleep was the culprit for the ADHD diagnosis. The site below covers most of the possible treatments, diets etc. It should be helpful.
http://www.healing-arts.org/children/ADHD/treatments.htm
The Boyfriend's nephew has ADHD and his mom recently started the Feingold diet. She's very strict about it and everyone in the family says that they've noticed a great improvement and it's only been 2 weeks. Yesterday, they went to Five Guys, which is an approved Feingold diet fast-food chain, but they won't be going back. They noticed a bit of the ADHD symptoms creeping back in. How is it working for you?