Hey ....
I had all these problems. This condition is known as hypocondria or health anxiety. It is hard to believe that our mind can convert our thoughts of feeling of heart disease into real physical symptoms.
It is first triggered by an event like a chest pain or left arm pain or any other thing. Then you start pondering over it thinking of worst situations all the time. Then you "GOOGLE" the symptoms and get to know about symptoms of heart disease. This is when you start losing control over the situation.
You will get chest pains, left arm pain, neck pain, shortness of breath, sweating. Then comes high pulse rate, palpitations and you start noticing each and every sensation of heart. You will check pulse rate time and again, your heart will start pounding. I even felt my chest bumping with heart beat giving impression that my heart was pounding so hard that my i can visually see my chest and stomach bumping with each heart beat.
Finally you convince yourself that it is heart diaease and you will get heart atta k anytime. You can do any work and cant sleep. You start treating yourself as a heart patient (it brings smile on my face now when i remeber myself pretending to be a heart patient).
I went to docs many times. Did all the test, ECG, echo x ray but doc said it was nothing but anxiety. Still i was not convinCED. It was when i visited this portal i came to know that it is a very common problem and millions of people have it with exactly the same symptoms as me. I was very relieved to know that i was not alone to experience such problem. Then i spent days reading and discussing my problem with people on this portal. Slowly and slowly my condition started improving.
I learnt about CBT. I would suggest that you follow the same and talk with people. But first without any fear and heaitation, visit a doctor and get yourself checked. After that when doc tells you are fine believe in him. Try Cognitive Behaviour Therepy or CBT. There are also android apps on playstore for CBT which are really helpful if you want to do CBT all by yourself without anybody else or a therapist.
Remeber the recovery will not be easy and fast. You will get over it slowly. Try distracting your thoughts away from your problem. Start walking or playing a sport or exercise. Slowlu you will get over it. You may feel its over but it can hit you again but its important not to lose your hope and again fight it and eventually it will vanish.
These things are not permanent and you can experience it again in few months or years but again rememver you beat it before and you should do that again. Dont panic.
Please google about CBT and you can be on your road of revival within no time.
You might be thinking why i have written such a long story of my experience but let me tell you friend that this is because i suffer from exactle same situation as yours and i know how hard and disturbing this thing is. And i dont want anyone to undergo this situation. I am 27 years old, am not fat, dont do drugs, have a very good settled family and a very good job. I am telling you all this because i want you to know that there is nothing for which i should worry but still i suffer from tension and worry a lit for everything and have this problem so any one can have this problem and you are not alone so dont worry.
Remeber to visit a doctor first and then get CBT and interact eith people. Hope you beat it soon. Cheers friend.