I wasn't sure of the appropriate group to post to for this, but I thought anxiety seemed the best fit. I've been suffering from tremors and stiffness for at least 4 years now (since the age of 16), primarily in situations involving social anxiousness or discomfort, and I'm really posting this just to see if anyone has any guidance or ideas on what may be wrong (I've been to a doctor and had some bloods taken, but they weren't sure either). I've written some of the details below.
Though I started to notice that I was having to strain my face to smile in the morning, the first time I really acknowledged these problems was when doing a speech at school 4 years ago. In the past I performed consistently well in public speaking (though I was always nervous), but from then on, I found that my body reacted completely differently to anxiety: my voice would become shaky and monotone, my hands would tremble, and my facial features would shake also. That year in school, I also found that I was struggling to sit still in classes and talks (something I'd never struggled with before), often finding myself in a state of discomfort, often ending going between seizing up and shaking, and sometimes feeling like my body was rocking forwards and backwards slightly. In the years to come I'd find myself facing my tremor under many circumstances, though as time went on I found it happening in situations which I wouldn't have seen as inherently stressful beforehand, like going to the cinema (whether with family or friends) or eating with friends (were I'd often notice a slight tremor in my hands).
As I mentioned, I've found that the tremor occurs even when facing a similar levels of stress to before it was an issue. Having said this, I've felt like a vicious cycle is occurring in many of these situations. Firstly, I become anxious that the tremors will come on, which in turn makes the tremors more likely to occur, and then leads to even more anxiety!
As I said though, I wasn't completely sure whether the anxiety community was the right place to make this comment though. I've additionally found that my body has become much shakier when under physical stress, such as when doing plank or press-ups, even though I was by no means doing those exercises more often in the past (In the past, I would always begin to shake slightly after doing these exercises for a while, but now I find that I start shaking vigorously almost instantly), Around the time I got my tremors, I also found myself occasionally having spasms in my neck without any clear reason (though I'm not sure if this is related).
There have also been some other very minor health related issues which I started to suffer from around the same time (such as heat rash, and slightly low iron levels). Beyond the time at which these issues started, I don't have any strong reason to think they're connected though.
Sorry for the long post! If anyone has any thoughts please say.