also: はらいた
General term for pain in the stomach or abdominal area. Both readings are common; ふくつう is slightly more formal/medical, while はらいた is more casual.
I've had a stomach ache since yesterday.
I stayed home from school because of a stomach ache.
I've had a stomachache since morning and couldn't go to school.
I ate too many cold things and got a stomachache.
I missed the meeting because of a stomachache.
My child suddenly complained of a stomachache, so I took them to the hospital.