I have a history of occasional heartburn. four nights ago i had a very bad flare up that caused significant chest/rib pain. the heartburn resolved that night but i still have some soreness in my chest, kind of like a side stitch. is this normal?

Heartburn reflects a change in the tissues where food enters the stomach created by a backwash of stomach acid. Like a scuffed knee, the "wound" is more sensitive when touched. In this instance any food passing by or any further acid backup. It will likely self heal in time & avoiding acidy fluids/spicy foods can reduce transient symptoms. Don't lay down after eating & reduce caffeine for now.