Cold belt

Having suffered motion sickness all my life, I've figured a few useful ways to, firstly, avoid it - but failing that, reduce the effects.
I find that most non chemical methods of treatment do nothing, the band which puts pressure on the p6 area of the wrist is entirely useless, and sucking a boiled sweet can occasionally bring down the symptoms, but I suspect mainly due to a placebo effect. The one thing I have found to work is bringing down my temperature in localised areas (That is, opening a window in the car rarely helps, but holding my hand out of the window, then placing it on my forehead or stomach can be quite useful).
Thus I propose the cold belt - the band fits around the waist, and has a large buckle area which houses the cooling element. This could consist of chemicals which undergo an endothermic reaction, but since I can't say for sure what chemicals would be used to do this and still be re-usable, I suggest that the front of the belt be filled with water.
The rigid frame at the front will cover the stomach with its largest surface area and cool down the wearer. The belt would be available as a headband too, covering and cooling the forehead - to be worn when needed, as the symptoms begin to appear, or as a precautionary measure as the journey is begun.