A great analogy and so true that these symptoms normally break through as a build up over the months and years.
I've been to the GP today and am going to be put on a 24-hour heart monitor. Hopefully I'll have it next week, as the GP saw I was distressed and put it through as urgent. She did say that she thinks my racing heart is anxiety, however. Even so, I've managed to wind myself up this afternoon that I have POTS as my heart races every time I'm vertical and doesn't go down until I'm sat or lying down. It can raise by 40-50 bpm just from standing and pottering around the flat. The good news is that my palps at night have subsided and now all I notice is a spike in HR when I roll over in the night.
I've also been given 10mg Citalopram to start taking. I'm quite nervous as never taken anti-anx meds and I'm worried my heart will go even faster on them. I guess I just need to bite the bullet...