Re: motion sickness or heatstroke?
My wife had a similar response to a long day boating last year. The equilibrium crystals in her ears had shaken loose.Had to go to a physical therapist/chiropractor for adjustment--twice.
My girlfriend fly's for a living, and has had these symptoms twice in the past. Both times were after very long (12+ hours), very turbulent flights.
The flight doctor diagnoses of the cause, was the same as Bart Sr. describes. He told her to see a ear, nose, and throat specialist. The treatment was rather strange, and did little to combat the situation, but it gave her the feeling she was doing something (no matter how silly it was) to remedy the dizziness. I think the guy (not the flight doctor) was just a quack, had no idea what he was talking about, and just out to make a quick buck. The flight doctor later questioned the doctors treatment methods & suggestions.
All in all it took several months for it to completely go away, and it still recurs (short term) from time to time, often after rather rough flights, or boat trips.
I grew up in the heat of the south and would consider the temperatures you were in, to be rather mild for a heat stroke.
On the other hand I live in Germany at the moment, and when the thermometer hits 70 degrees here, they start to pass out, and claim they are all experiencing circulation problems & heat strokes.
