No, I wasn't dehydrated
I was drinking water like a fish. But the long drive home without an airconditioner really did me in (I work in the city but live in the outer suburbs)! I think it was a mild heat stroke. The same thing happened two days later, despite keeping water and ice on my face/body and continually drinking all the way home. My car is fixed now though (it turned out that the idiots who replaced my radiator just a few months ago installed a European radiator that was not designed to deal with Australian conditions, that was why the car was overheating and I could not use my air-con).
Yes, I do take prednisolone (prednisone).
I am also definitely much more susceptible to the heat since transplant, I have never felt actually weakened by the severe heat in the past. Clearly, I do now! Oh, and the Wednesday that I sent the original post ended up being 47 degrees. Ouch.
You'd be pleased to know that this week our temperature on average is literally HALF of last fortnight's. In fact, it's been downright cold in the mornings/evenings.