You didn't happen to tweak something doing some activity just before this started, did you? Because what you describe sounds more like muscle pain than anything heart related.
Actually you would be better off fighting the anxiety by getting up and being active because exercise can give a person a mental high for a while after or at least break the anxiety for a period especially if you enjoy the activity.
Since the EKG says no problem, then it is anxiety making you tense up and over-analyze your body in fear which makes it all gt worse the more you start noticing the ouches.
The fact they are intermittent means it is just mental, so perhaps you can dwell on that and relax.