So, this is a moderately long story so bear with me.

I used to have occasional problems when I smoked weed.  Once out of every 15 or 20 times, I would get a severely fast heartbeat and what I would describe as a panic attack.   Now im having a similar issue, but without the weed.  Over the last 3 months I've been having problems with extremely fast heartbeat, tingling sensations in my fingers, shakiness, twitching and shortness of breath.  I actually woke up at 3 am one night and thought I was having a heart attack, called the ambulance, went to emergency...  EKG, blood tests, everything turned up completely healthy.  I was dismissed from emergency.  Same thing happened again a week later.  I was given a holter heart monitor for 24 hours, came back fine.  No issues.  

I went maybe a month, feeling fine, then it happened again.  Since that most recent attack, I haven't felt right at all.  I'm completely messed up.  I get shaky, I have tingling in my fingers, I get a rapid heartrate for no reason, out of the blue.  My doctor has told me its anxiety and prescribed me beta blockers.  I'm not so sure.  I dont consider myself nervous or anxious about anything.  These episodes have no trigger.  I'll be sitting on my ass, watching TV or eating dinner or talking to a friend on the phone, or sleeping, and suddenly feel these sensations.  Heart rate elevates, start feeling twitchy, tingly, tightness in the chest.  Is this a normal effect of anxiety?  To be feeling fine and all of the sudden your body just goes nuts?  

The beta blockers... I hate them.  I was prescribed 40mg propranolol to take "when I need them".  When I take one it feels like I can't catch a breath.  I had to cut them in half, and when that didn't help into quarters, to be tolerable and even then I still feel like I can't breathe.    

Not sure what I'm looking for here.  Doctor says its anxiety.  I was more worried its the first signs of some horrible disease.  I just want to see if anyone has a similar experience.  I always thought anxiety came from... you know, feeling anxious.  And I don't.  

Male, 40, Canada.