What can cause a fizzy sensation in stomach? no pain just a fizzy feeling and nausea. haven't been drinking soda.

Reflux or gastritis: There are dozens of possibilities as your symptoms are vague & you need to give us a lot more info. It's best to see a MD as you may have gas or an allergic reaction to something you ate. Alcohol, spicy foods can aggravate stomach dyspepsia. So most would say rest, take lots of fluid, water and/or gatorade to start. Then slowly introduce liquids like soup or jello before moving to crackers/bread.