If it's just the stomach you probably have gastritis it's simple inflammation but with fatty foods and especially alcohol, it can easily be exacerbated to the point of you think you're dying. It could also cause an ulcer, and sores can turn cancerous it'd probably be best to alkalize your body. If it's a chronic thing it could also be an abundance of H. Pylori bacteria which is easily treatable this day and age and can also lead to ulcer and possible cancerous cells.
If it's in the lower right quadrant, if you've been vomiting bile with uncontrollable nausea you could be experiencing gallstone symptoms or even pancreatitis, and should go to the dr asap before it turns into a $100,000+ hospital stay
Or it could just be a regular ol belly ache and you have a vagina and should just handle