dear
@Bunnehbunn ~ at times I have chills which are more severe by far than any cold I experienced pre-ME/CFS (and I was raised in thunder bay where winters were -10 or -20 in the days before windchill factors were put into the equation. I'd have shivers and teeth-chattering until I sat by the fire and drank a hot liquid but within 10 mins, it would slowly recede and right as summer-warm rain again within 20 mins
for sure).
in these years of depletion and symptoms gone awry, I have no ability to tolerate cold whatever and if on a fairly low ebb, cannot even 'weather' {
} the coming-on of the shift to a cool summer evening if the day has been hot. but the alarming,irrepressible, shuddering under many-blanketed chills, those hit for hours and there's no turning them around or hiding them-- they stop the day and, as they're on of the obvious symptoms--even alarm others (teeth chattering under blankets when there's a warm breeze through the window is unmistakably occurring...).
my instinct is that
@Judee is correct in thinking "I also think chills are part of a shock response when our body is going into crisis like maybe hypoglycemia, adrenal, low electrolytes, drastic change in bp, etc."--- that they're a real warning sign to be gentler to the system in many/every way you can muster/dream up.
my experience also resonates with
@RebeccaRe and
@Shoshana , who find preventing getting cold in the real world/on the outside is a massive help. for me, it's not so much the feet (though I wear thick wool socks all the time in the winter and double them if feeling the warning signs of a crash hovering in my orbit)....but my head. even though I have very thick, long hair, I really can't go out in winter without a hat and if the actual weather is brisk, then a hat under a down hood. but for prevention, when feeling even a low ebb (pre-actual warning symptoms), I wear a toque indoors summer or winter and this seems to reduce the likelihood that the ebb will progress to a crash. maybe it reduces strain on the system?
best of luck to you~*~*