Welcome to the forum.
The commonest cause of fluttering sensation above the belly button is gastritis
(gas formation ).
1. Avoid caffeine, hot oily spicy food, drink water 45-50 minutes after meals ( avoid immediate water intake after meals).
2. Avoid eating refrigerated food, eat fresh home made food, veggies,berries, nutritious wholesome meals.
3. Try to be active, avoid sedentary lifestyle.
4. Take antacids and keep yourself well hydrated.
5. Keep bowels clean.
6. Consult a doctor and get fitness tests done to detect any abnormality in the report.
Get treated, take care.