Is it permissible for someone suffering from a migraine to break their fast if it causes severe headache and nausea that incapacitates them from performing their duties? Is breaking the fast in this case considered deliberate, thus necessitating expiation? And what is the ruling on continuing to fast or breaking the fast in this situation?

A sick person is permitted to break their fast if they experience severe, unbearable hardship, or if they fear an increase in their illness or a delay in their recovery. They must make up for the missed fasts after they recover. Fasting with such hardship is disliked but is valid and suffices.

As for a mild illness, it does not permit breaking the fast. The illness that permits breaking the fast is a severe one that increases with fasting, delays recovery, or from which harm is feared.

Intentionally breaking the fast in Ramadan without intercourse does not necessitate expiation (kaffarah) according to the majority of jurists; rather, it requires repentance and making up for the missed fast.