Commonly the stomach and digestive system is affected by stress. Either we don't eat properly or comfort eat and consume too much. Digestive acid levels are affected by stress as the fight/flight response will shut down the digestive system temporarily.
Putting food into a system that is not producing acid will cause discomfort, bloating and nausea. Simple rule of thumb: take a short walk to de-stress before eating, eat when hungry, chew thoroughly, don't drink water with a meal (it will dilute stomach acid), and don't smoke just before a meal (it will trigger a f/f response shutting down the digestive process again).
Using a digestive enzyme supplement can help digest food properly. If the stomach is producing too much acid and sensitivity is occurring use the herb Slippery Elm to line the gut before eating. The tissue salt Nat. Phos. is a good antacid balancing acidity.