I have similar symptoms but it started with feeling pins and needles all over my body, along with random muscle spasms everywhere and these internal tremors that seem worse in my chest and abdomen but are really everywhere else too.

I also experience constipation (but have for years without any other symptoms so not sure it’s related.)

I too have been struggling with anxiety and depression. But I’m not sure if that’s the cause of my symptoms or if my symptoms are causing anxiety. Still worth admitting that this follows a very stressful traumatic time in my life and I have noticed anxiety produces similar tremors or at least makes it worse. Yet I doubt it’s fully caused by anxiety due to symptoms worsening while I sleep.

Anyway be careful when they say within range because it took a few doctors to finally tell me my b12 and iron was actually low. Even mildly low levels can cause symptoms.

I have noticed mild improvement since taking high levels of all vitamins for a short while, at least I can sleep now and I couldn’t sleep at all before due to the symptoms. The pins and needles are a lot less pronounced and now i just have internal tremors.
Today though the internal tremors are worse, and I feel noticeably shaky accompanied with muscle fatigue and so I’m just kind of doubting it’s due to vitamin deficiency because I’ve been taking vitamins 3x daily for quite a few days now. Granted my doctor said it could take a month to notice improvements

So just fyi ask to see the numbers on your b12 / ferritin and get your other vitamins tested. For example on my blood test, the b12’s range said in between 150-600 is normal. Mine was at 162. And so a few doctors overlooked it until one said 162 is actually on the low end. Everywhere else says the range should be 200-800 and being mildly low on b12 can produce symptoms even anxiety.
Also my ferritin was mildly low. I assume I probably am low on other vitamins hence why I started taking all vitamins.
(I don’t really have a well balanced diet just because I never ate on a regular basis, fasted a lot and hated cooking meals)