You are not alone. I have had panic attacks and I have had tachycardias and just plain heart palpitations. The symptoms of a panic attack are very similar to heart palpitations, tachycardias,etc. Whichever it may be, it can freak you out. However, note that in a majority of cases it is benign - meaning not harmful. Freaky but not harmful. The most important thing is the doctor has not found anything wrong. I was put on a 48-hour monitor and it did not catch anything. However I was then put on a week constant monitor and, though a pain in butt to wear, it caught my pvcs and get it corrected.
You MUST calm down. Start walking after work or do some exercise as it really helps if it is panic attacks. Gets the seratonine and endorphines kicking in to calm you down naturally.
Please try to calm down. What you are experiencing is classic anxiety, I know, I have had most of these symptoms myself one time or another.
Anxiety and these symptoms can appear out of the blue for no reason, there does not have to be anything serious for them to occur.
Just try to relax, I know, easier said than done, and know these are normal for anxiety. I do not think you are going to die, so try to focus on happier things. :)
Oh yes, there is a great anxiety forum here, you might want to check it out, I am on there too.
Your not going to die!!!!!!!!!! Erase that notion from your head!