I get odd symptoms when i move my neck too - and it is my neck as i've tested it when my head was stationery and moved the rest of my body.
Basically my upper cheeks flush/blush and my heart rate goes up a little, ie an adrenaline rush, + i get a release of sweet mucus at the back of my throat on occasion too, actually thats rather pleasant
It really doesnt matter at what speed i move my head or whether its left or right, up or down.

It doesnt affect me in any other way that i've identified.
My cheeks flushing was a very marked symptom in the first couple of weeks post injury (sweet taste came 4 weeks or so in, have a theory i was in ketosis at the time to explain sweet taste and that somehow the taste got imprinted in some fashion despite getting out of ketosis - Drs here are a bit baffled!) but now is fairly mild although its been at this "level" for some time now.

do you reckon i should avoid provoking these symptoms?

that would make further neck rehab rather difficult of course and i'm v keen to continue this as I've identified that my dizziness in particular is stemming from my neck

many thanks!