Can low dopamine cause twitches, tachycardia, memory issues, brain fog, personality change...?

Hard to say... Dopamine (DA) is not measured in clinical labs. It's extremely rapidly metabolized along a variety of pathways. Further, DA levels in blood bear little resemblance to DA activity in the brain - even less to the small brain regions and synapses where DA signaling is concentrated. Though DA *might* be relevant, the symptoms you describe could have a very large number of non-DA causes.