I woke up with real bad chest pain once when I was 28. I freaked out and went to the ER. They made me sit for 4 hours and wait. By the time a doctor saw me I felt fine. They did an EKG, confirmed I was fine, said it was probably anxiety, and sent me on my way.
I did some research on the net myself and determined it was heartburn. I had been drinking a ton of coke at that time and eating a ton of fast food, so made sense. But in the moment I was definitely scared shitless.
Also, when hospital sent me the medical bill it was $600. LOL. Luckily, my copay was only $50.