What is palpitation of heart ? Some more facts about it and precaution and tests to be taken ?

I'm a 24 year old male (from Chennai). I experience symptoms such as breathlessness, pounding feel (in the chest), etc. when I get anxious (such as being involved in a tense situation) or excited (such as attempting to sing in a party, getting to the stage to receive an award, etc.). Once I calm down, these symptoms disappear and they generally don't last for more than 2 - 3 mins. Sometimes I feel like being unable to breathe for a fraction of a second but get normal after that. I have experienced these symptoms several times over the last 7 years or so. I also experienced palpitation once in Dec 2005 (lasted for about 15 mins) and once more recently in July 2010 (lasted for an hour). For long, I thought I was perhaps suffering from a heart problem (I never met a doctor though), but off late, I learnt on the net that there's something called an anxiety disorder whose symptoms are similar to cardiac symptoms. That had me wondering if I too could be sufferring from an anxiety disorder. I want to meet a doctor to get myself checked up. However, for some reason, I feel nervous about meeting a doctor. I fear that on entering the doctor's room, I might get tensed and experience breathlessness, palpitation,etc. I feel if I can contact the doctor over email/phone,etc and introduce myself before actually meeting the doctor, I would feel better. Since I live in Gopalapuram (Chennai), can someone help me in this regard?

So this has happened to me 3 times in a year...so far. a day before getting my period I start having arrhythmia's. It was a Friday morning and it all began , I could feel every heart beat . Saturday morning I got my period. The erratic beats were constant and lasted until Monday and then slowly started to tapper off with my period. During this time, I had to stay clear of all caffeine or I felt even more awful, with dizziness , headaches, pressure in my chest and head on exertion. I remember this happening before 2 times and then I realized it also was during and around my cycle time. By the time I got into the Dr's office and went for tests it was too late , things had stopped. Please give me some insight and what to do to not suffer this again!
Sincerely Cindy in Canada