I think I know the feeling you are trying to describe., or something similar. Your not nuts
Its a horrible feeling, uneasiness,unsettling, kinda like having restless leg syndrome in the chest area. I haven't had it in a while thankfully.
I thought it was adrenals at first , but not sure.
For me its like gloom and doom in my upper body.
I didn't have the twitching with it, but I have had twitching before.
I don't think it was anxiety, that came after the feeling ,because I hate the darn feeling and the feeling worried me. Like you said it was unsettling.
Hope you get rid of this soon and back to remission.