hi shirley. i looked into all this when my hot flushes started, yours sound very much the same as mine were for the first 12 months or so, i used to think of it as something like an adrenalin rush just before the heat kicked in, like the 'fight or flight' feeling.
our adrenal glands are situated just above our kidneys, somewhere above the waist but under the breasts, and that's just where this feeling would start with me, i can put my hand right there in the middle about 6-8 inches above my navel, kind of where my ribs join. the adrenal glands receive regulatory input from our nervous system, and during menopause the automatic controls of the nervous system become erratic so it makes sense to me that that's why we get this 'adrenalin rush' feeling and then the hot flush. you'll probably find that these feeling change after a while, and the length, frequency and intensity of the flushes too, sometimes feeling less hot and at other times feeling as if you're going to burst into flames!
hope this makes some kind of sense to you
sue