I had a similar situation. I thought I was having a heart attack and got a ride to the hospital. They whisked me right back there despite the fact that I was so young at the time that the odds of it being a heart attack (according to the ER doctor) were infintesimal. It turned out to be non-cardiac in origin, BUT it turned out to be something almost as bad - a quickly spreading infection that was in my lungs and bloodstream.
Aren't you glad this didn't happen to you 75 years ago?
Yikes! Are you okay now? I've seen that before, and it's scary as all getout.