Mmm. Then there are eating disorders, migraines, even excess of alcohol. All relieved by the placement of fingers in throats.
Migraines will invariably bring involuntary heaving/vomiting.
Eating disorders are an entirely different condition and self induced after eating.
Alcohol, much the same as migraine.
Nobody would stick their fingers down their throat unless they were neurotic and trying to prove something as it's not the norm in a healthy person. JB was/is probably not a sickly person and stopped himself from throwing up, but as I said his stomach would have been empty anyway and he'd just have wretched.