Functional dyspepsia (dis-PEP-see-uh) is a term for recurring signs and symptoms of indigestion that have no obvious cause. Functional dyspepsia is also called nonulcer stomach pain or nonulcer dyspepsia. Functional dyspepsia is common and can be long lasting — although signs and symptoms are mostly intermittent.
https://www.mayoclinic.org/diseases-conditions/functional-dyspepsia/symptoms-causes/syc-20375709