That persistent pain, what is it?

So you get up in the morning and go about your usual tasks and then after a while realise there's a dull, persistent pain in your chest that wasn't there earlier. It must have crept up on me, I don't remember it starting.
After a while I began to dismiss it to a gastric problem due to it's persistence, and arguably wanted to disregard a cardiac episode, the pain just didn't seem "bad enough" , it was just annoying and prolonged.....