Can gastroparesis cause pain not only in your stomach on the left side, but in your left chest and shoulder too?

Theoretically, it can, but that is not the usual symptoms of Gastro paresis. Usual symptoms of Gastro paresis include symptoms that would be related to being full all the time, such as boarding, gas, or a feeling of early satiety when eating. Eventually, it can also cause pain, however. If you think you have gastroparesis, see your G.I. doctor. Good luck.

I fully agree that you should consult a gastroenterologist to obtain an accurate diagnosis as your symptoms are not characteristic of gastroparesis. It there's a stomach problem causing that distribution of pain, I'd be concerned about partial gastric obstruction possibly at the gastric antrum. The specialist will order or perform appropriate testing.