I know this conversation occurred a while ago, but I just happened upon it. I've had a similar experience, heat stroke (and dehydration) that has left me with a severely diminished ability to tolerate heat, especially when coupled with exertion.. and a significant intolerance to cold as well. This has been vexing, though often the effects aren't felt till hours later. I'm extra diligent about proper hydration, especially of the electrolyte variety.. but I'm still susceptible to the heat. And it's been about 6 years. Have you had any success finding information or docs that help with this? -ds