I know tremors are common when you take lithium (I take 900 mg a day), but the past year I've noticed it's a lot worse and I don't know if it's the lithium or something else.

Just a few background points:

I first noticed tremors in 2019, about 3 years into taking lithium. It happened when I was dehydrated, and after I drank a ton of water, it went away, so I assumed the lithium was the cause (more exactly, when I raised my left arm to about chest level, it would start shaking uncontrollably. It was only my left arm. This still happens, and drinking water stops it.)

Now any time I do any kind of exercise like yoga, my legs start shaking very badly.  I find it difficult to hold a pose because of how hard they're shaking.  I don't think I have any muscle weakness, though, as I am capable of running 30 minutes nonstop with no shaking and no muscle pain.

I've had my lithium level checked twice since this started and both times it was low (0.4). My psychiatrist see this and then just dismisses it. I've also been to a neurologist and was told it was stress and that I should "take a Valium every day". (wow thank you, now whose gonna prescribe me that??)

So my question is, does anyone else have any experience with this/is this a common side effect of medication (I also take 100mg of Seroquel and 2.5 mg of Ativan every day) or should I look into seeing a doctor about this?