In the past 5-6 years or so, I've about 4 episodes of symptoms that are somewhat troubling. Basically, I start to feel extrememly dizzy (vertigo) and notice strong heart palpitations. Each time this has happened I've been sitting down (in class, at work etc.) and it just comes on suddenly. On one occassion I happened to look at my my hand first and it was completely grey - looked like no blood circulation. It frightened my friend who was sitting next to me (and me too!).
The dizziness/palpiations last for a short time but then I feel quite awful - exhausted and shivering. In the days that follow I feel exhausted and have a heavy sort of feeling in my chest. After a few days, I feel back to normal.
I visited a clinic after one episode where my heart rate was found to be quite high (140+) and took a while to come down to normal. In the days that followed I had an ECG and blood tests but all came back normal. There was never any follow-up.
I am an active person with a healthy weight. Don't drink or smoke.
Anyone ever experience anything like this? Not sure if I should bother going back to a clinic as I expect the same tests with the same results.
Any ideas would be appreciated!