What Causes Vomiting And Fecal Incontinence In A Person With Down Syndrome?

MyDown Syndrome son 31yo thew up after lunch o Friday. Lied down on floor lsot total control of bowels and threw up some more. Got cleaned up, slept off and on for 3 hrs and hten acted as if nothing happened. Thsi has happened 3 times in last 5 years. Has been monitored for cardiology and nothing found.