What Causes Pressure In Chest, Stomach, Esophagus And Upper Back?

Hi, I have been experiencing feelings of emptiness, combined with great pressure in my chest, stomach, esophagus and mid - upper back. It predominantly felt localised in my right side. This pressure feeling also occurs around the diaphragm area sometimes simultaneously, but, more commonly on its own, usually during some kind of exertion. I have also been experiencing more gas/bloating. Any ideas would be really helpful? Thank you :)