Your description here of the "heat wave" definitely sounds like it could be a hot flash, a sign of menopause, and you are of the "right age" for that to be happening. Hormone flucuations during that time can cause all sorts of odd symptoms to occur, including memory problems, blood pressure problems, other stuff. Presumably your doctor is checking or has checked you for that, although very often blood tests come back normal, when in fact you are dealing with menopause. They did for me.
Are you having any problems with your monthly cycle, like missing a cycle, or unusually heavy bleeding, or sporadic bleeding, or anything like that? Those would all be indications that you're moving through menopause, too.
Usually when I suffer an MS-related overheating, I clearly have been in a phyical situation where it is hot, like outside in the sun, or in a closed room with limited circulation....not in ordinary circumstances in an office...