Unreal that none of the current comments are advising breaking the fast.
I mean, sure, it is likely that this is an electrolyte issue. But, are we sure enough to risk this person’s health? An elevated heart rate and trembling hands can be serious.
Is sustaining the fast so important that we would recommend rolling the dice on that rather than breaking the fast?
Most likely an electrolyte deficiency.
I’d suggest you drink something with high potassium and sodium.
Drink slowly - don’t chug - you’ll just pee it all back out really quick.
If the palpitations continue, see a doctor or go to the UC.
Very likely though you’re just low on potassium.