I have a recurrent pain in my esophagus/sternum area. Could this be acid indigestion and what foods are triggers?

I am under tremendous stress lately. I seem to have on and off again pain in my sternum but also lower down. I did have two EKGs and it doesn’t appear to be heart related. I have also been carrying a heavyish backpack on some trips but the last time was several days ago. The doctor felt it was musculo-skeletal. Could this be acid reflux and if so, what do you recommend? It doesn’t feel food related; I am eating very small meals.