If it is some consolation, I can relate. Like saraeli says, I would say it's dysregulation of the autonomic nervous system (not a doctor, just read a lot...)
all the nerves involved with regulating bodily processes and/or responding to stimulus, get damaged so it's like a car with bad/damaged wiring, the A/C/heat turns on/off, thermostat gets bad readings or no readings, car overheats or freezes up...that would be my way of explaining...I think it's the combo of myelin disintegration and toxic load of abx, when the pathogens die they leave toxic chemicals in their wake...and much misery.
However, I would say based on this chart during acute phase or re-activation, and during Herxs it's more intense...during Herxs etc. in the past I did very similar, wore a hoodie trying to do yard work in 80-90+ heat...
it is startling, alarming, disturbing when your body does this, you get chills seemingly out of nowhere, or not because of temperature...or danger...or a 6th sense ...but something else (!). That something else is very unsettling indeed! not to mention the neighbors think you're nuts.. *sigh
https://www.neuroborreliosis.com