Dear Robert,
I really want to say I can totally understand how very frightening and frustrating all this is for you. I had a triple bypass 20 months ago, so I do know a little of heart issues.
I obviously can't comment on the results and technical terms that have been used by the hospitals in your case. The thing I wanted to suggest is that you ask them next time (I hope there isn't a next time but in case there is) if there is a chance that you are having attacks of pericarditis.
I have had these attacks on and off for a number of years. The pericardium is the sac that is around the heart. It can be inflamed or infected, and believe me the pain that is given off is unbelievable. The symptoms are so much like a heart attack, which I can comment on as I have had 2 of these, but because the pericardium is not a muscle, it doesn't show up on an ECG. It gives rise to a sick feeling and when you are indeed sick it is normally a horrid tasting bile that comes up. Does your pain recede a little when you lean forward? If so, this is because the pressure is shifted in the sac when you do this. Normally, there is heard a scratching sound that they term as a "Rub" when you are examined with a stethoscope. I really do think it is worth speaking about to the doctors.
From the symptoms you describe though, this is what it could be.
I am not a medical doctor and I am not diagnosing you, but speak only from my own experience of this If you are able, please do suggest this to the medical staff.
I would be interested to hear how you get on. I too am in the UK and know first hand the difficulties the NHS presents us with at times. Please insist that they listen to you, only you know how you feel, perhaps then suggest what I have told you about. It can't do any harm, it might even do you some good. I hope so.
I hope you are ok.
goldenwings