Made Familiar: Grandma is Sick Level 3

Musembei and Anna visit their grandmother in the village. They find her sick. She complains of constant stomach pain. Their uncle also_x000D_
complains of stomach pain. Their home is clean. They also maintain high level of personal hygiene. What could be the cause of the_x000D_
constant stomach pains? Musembei and Anna want to find out.