It can not be a possible that somebody have got electric shock in childhood and the symptoms starts in adult stage or later. Your current issue must be due to the lifestyle. You can go for proper heart health check here they will take your ecg and will also suggest for some blood test and see if any thing gets evaluated. Also do not forget to check your cholesterol, BP as well as sugar, you can also check TMT(treadmill test) to know better way your heart capacity..... And have balance in 4things, diet, exercise, rest, and positive attitude. Take care.