Does intentionally vomiting before the dawn call to prayer (Fajr) or after the imsak call to prayer invalidate the fast in Ramadan for a patient with irritable bowel syndrome (IBS) seeking to alleviate their pain?

Intentionally inducing vomit invalidates the fast according to the majority of scholars. Whoever vomits intentionally must make up for that day. This is supported by the Prophet's (peace be upon him) saying: "Whoever is overcome by vomit does not have to make up [the fast], but whoever vomits intentionally must make it up." If the intentional inducement of vomit occurs before true dawn, there is no harm in it. However, if it occurs after the true dawn becomes apparent, then it breaks the fast and requires making up the day. If the intentional vomiting occurs after the first call to prayer but before the second call to prayer, the fast is not invalidated by it, because the second call to prayer is what marks the prohibition of things that invalidate the fast.