My son have a rare genetic disorder.. derivative #7 Chromosome, monosomy 7p22.3 and partial trisomy 11q22.3.. When he tries to make a bowel movement, his body tenses up and he vomits all of his food.. He cries alot afterwards.. As though it pains him alot.. Why is that??
The significant amount of annoying vomiting indicates underlying intestine narrowing either at ileocecal junction or upwards which gets compression during bowel movement pressure and giving reflux vomiting.
A CT scan of abdomen & pelvis is the gold standard non-invasive evaluation required to get the basic clue.
Do remain in follow up as I am keen to know about the rare disorder.
Hope I have answered your query. Let me know if I can assist you further.