Sudden bout of gagging and nausea and feels like someone is pushing in on my stomach just below the breastbone and some belching.

Acute dyspepsia.: This acute finding could be one of a few things, and management will really depend on how today goes. This could simply be heartburn from something you ate last night - perhaps too large a meal or too late eating. Could be a gastroenteritis beginning, and if so vomiting and diarrhea may follow. If you start vomiting a lot or have bad diarrhea, see a local doctor right away.