Anxiety Support Group
Anxiety is a physical condition marked by intense and persistent feelings of distress, fear, angst or dread. General anxiety caused by routine day-to-day stresses usually passes quickly and is experienced by almost everyone at one time or another. However, such feelings that linger over time and are very difficult to cope with, and which lack a clear cause, may indicate...

If you're really worried, you could try talking about it to your GP ? For what it's worth, in spite of experiencing intense fear over this, I'm still not dead yet.
So definitely talk to the GP. :)
Next time it happens just stay calm and put ur mind on something else.......I know that sounds stupid because it is a very terrifying experience........ but when it happens again just keep it slow and relax
Your not going to choke to death. Not today, tomorrow or ever. Just tell yourself that