I consider myself to be a fairly fit 34 year old, with no history of major health problems, however, about a week ago, I fell ill at work, was admitted to hospital (discharged the same day) and have not felt right since. I am concerned that something may be wrong that hasn't been diagnosed correctly...

Background on what occurred:

I sat down at my desk to do some computer work and after a minute or so I felt a sudden 'rushing' feeling whicih felt like it originated in the middle of my chest (ie; my diaphragm or sternum). There wasn't really any pain involved, but it was very unsettling as I had never experience such an intense feeling before. It brought on an immediate feeling of weakness and made me feel like I was going to black out, although I didn't actually lose consciousness. I briefly thought that this may have been a heart attack.

After this sudden rushing feeling I had a vague feeling of nausea and light-headedness. I then kind of stumbled to the ground and by this stage a colleague called an ambulance. While I laid down, I regained my composure to some extent. The ambulance eventually arrived and took me to hospital (as a precuationary measure).

Outcome:

Many ECG's and blood tests were done at the hospital and they all came back normal. The treating doctor said that I could not have been under cardiac arrest because "the enzyme and electrolyte levels in my blood were normal". He said that I did have a low heart rate (which is pretty normal for fit people) and was fairly dehydrated (I was put on some fluids). He said the episode I had may have been caused by something viral. After a few hours I felt normal again and was discharged.

Now:

There are times throughout the day where I continue to feel slightly ill. By this I mean that I experience slight discomfort in my diaphragm which brings on a vague feeling of nausea, but not enough to make me physically sick. The feeling also makes me light headed at times. I feel that these are mild relapses of the episode I had at work, but without the rushing feeling I experienced while at work.

Lastly, while I don't know if it is related, I also experience some discomfort in the heart occasionally. I can only describe this as a slight ache (not pain) that lasts for a few minutes. I would experience this maybe once a month or so. I had this checked out last year, and the cardiologist ran an ECG, an ultrasound, and a 24 hour holter monitor. All tests showed that my heart beats normally and my valves etc are clear.

So what is this ongoing feeling I have since last week? Could something be wrong? Should I not worry about my heart as my doctor suggests? Will this vague feeling of sickness go away? I would appreciate anyways input, especially from if its from a knowledgable source.

Thanks guys.