I get them too
Started when i moved from Durham to Surrey, went to doc's down here and he said i had done too much all at once ie move away from home, get a new job, moved to new place etc etc
I have my panic attacks under control now, without having to use tablets as well, but i still get this fluttering now and again, which i do put down to stress, even tho i dont feel stressed.
I stopped having caffine i have all de-caff products now tea, coffee etc and feel a lot better for it, just got to get my diet back on track.