Pain often has no memory, but I recall the first episode very clearly. It was an intense, radiating pain throughout my left, upper chest area. I could not take in a normal breath without excrutiating pain. Although I was only 21 at the time, I was convinced I was having a heart attack. Off to the MIR (I was in the military at the time), where an EKG was performed. I was told it was pericarditis, prescibed what I believe were antibiotics, and returned to my unit. Several months later, the same thing - only this time I didn't bother going to the MIR. I found that if I ignored the pain and simply took a huge, quick intake of air, the pressure or whatever it was disappeared and I was fine.
Does this sound like what you experienced?