A functional gastrointestinal problem, where food or other stomach contents effortlessly comes up into the mouth, where it is either then vomited, spat or swallowed. Odour may be a clue.
Diagnosis is on history, but often misdiagnosed as reflux (and resistant to reflux treatment). Typically no nausea, no nocturnal symptoms, no dysphagia but these do not necessarily exclude the diagnosis.
Treatment is diaphragmatic breathing! Baclofen has been used.
Rome IV criteria. Beware eating disorder.