My wife was also struck down with something during our last trip to Disney. Immodium didn't help and she eventuall saw a local doctor in Orlando, and her own doctor when we returned to UK. two and a half months later it still isn't cleared up completely.
The doctor in Orlando said it was unlikely to be anything we ate at a restaurant. The reason being that whenever a restaurant serves contaminated food, many people ar taken ill, and all the local doctors get patients with the same sysmtoms after eating at a certain restaurant. All the doctors talk to each other and word spreads around the medical community fast and everyone knows which restaurant was the culprit. My wife's case was isolated.
We may never know what caused her problem, maybe she caught something on the aeroplane, maybe she picked something up by touching a tap in a bathroom. We will never know.
I don't believe that it was a Disney restaurant, because there were no other cases locally at that time.
Andrew