Some thoughts:
Tiggerlover, you say your son's symptoms are fairly recent in onset, and seem to coincide with increased intake of Fanta. The first thing I would do is cut out the Fanta for a couple of weeks and see if it helps! ADD/ADHD children show signs of the syndrome in early childhood, though it usually doesn't get diagnosed until they get in school. Food allergies can look like ADHD.
Yes, there are lots of parents of ADHD kids here! Wonder if they got it from all of us high-stimulation craving Disney lovers? The perfect ADHD vacation wouldn't be lying around on a beach, that's for sure!
We have been in this battle for five years now, since my DD was diagnosed in 2nd grade. She's got the "checked out" type, and last summer we finally got her tested for Auditory Processing Disorder as well. She has a severe deficit, meaning she just doesn't get spoken language most of the time, especially if there is any other noise. You can imagine what this does to her in the classroom, not to mention socially. She gets no help at school, and is not considered LD because she still manages A's. She's highly gifted and compensates. So it's up to us to figure out how to help her survive at school. Earlier this year, we found out she was having regular meltdowns at school! She has a history of mood swings, so I was afraid she was Bi-polar too. Turned out that a new medication we had her on was the culprit.
Since that scare last fall, I have started to give her twice daily doses of high quality DHA/EPA Omega-3 - fish oil. I think it has helped tremendously. Just last week she had a social crisis at school that lasted for days. It involved being shunned by friends she had known for years for no good reason. She handled it so well, sad but philosophically. Things changed again this week for the better (mid school girls!), probably helped by her mature way of handling it.
She's on the honor roll with a 4.0 average so far, and on a competitive dance team with kids 2-3 years older. She loves dance and has a talent for it, and I really think daily strenuous activity helps with the ADD. She also takes her medication every day, with an extra dose for heavy homework nights. In contrast, my very bright, athletically gifted nephew may not be able to play sports in high school due to poor grades. His parents refuse to medicate his ADD. I don't understand preferring dropping out of high school (a real possibility) over medication, but that's just me.
It's a continuing war, but just think how creative, energetic, and truly sweet your kids are. My DD would never treat a friend the way she has been treated many times. She's loyal and generous to a fault. I'm going to do everything I can to help her make it in this world. And we're giving her some great family memories of trips to WDW!