I've struggled with anxiety for years, with all sorts of physical symptoms. A few years ago I experienced a trauma and major surgery. When I was recovering in hospital I started to get this feeling like I was shaking or vibrating inside but no one could feel it externally. It was so strong it felt like the bed was physically vibrating. The doctors and nurses all looked at me strangely when I described it and had no idea what I was talking about.
It carried on for a while, to the extent that I saw a private neurologist as I was worried it was something like Parkinsons. He couldn't find anything wrong with me.
I later found out that it is a symptom of anxiety. I thought it was odd that none of the medical staff I described it to identified that it is a fairly common anxiety symptom.
It eventually went away but I've had a stressful time recently and it has come back. It's not as bad as it was before, but seems to originate at the back of my neck/upper back. It's much much worse when I wake up from sleeping which seems odd as I would have thought that is when I am most relaxed. Although I do grind my teeth and clench my jaw in my sleep so wonder if there is a link there.
Anyway, I'm just curious of other people's experience with this weird symptom. Would be really interested to hear from anyone else who has experienced it.