yawning and shaking

Factual Questions
1

sometimes when i yawn i shake, involuntarily. but i’ve never taken notice at the time if i’m cold. all i know is, i just did it, and i’m not shivering. but it’s chilly.

is there a reason that this happens, or is it a mystery on the level of why we yawn?

2

I do this too, but not for every yawn. It feels like a shiver, but it’s not a cold-induced shiver. I’m curious too.

3

Some medical experts feel its related to the famous “piss shiver”, and it’s about as well understood