I started getting palpatations about 4 or 5 months ago. I went to the doctors during an attack of em as I was close by, they were so strong they assumed I must actually have a heart condition.
However, when it came about they are stress related, they took me really seriously. I know its the situation I have been in that has caused mine and as my life has improved so have the panic attacks. There are all sorts of things that can help you if these episodes continue, if you feel there are no actual external causes. Counselling, anti-depressants (there is no shame in taking them if you need them).
To describe an attack, I would start getting breathless then my heart would beat quickly, then stop for 2-3 seconds then start back in again with a massive thump, then cycle like this till the attack was over.