looks like gut motility problems. Bothe the upper gut and lower gut are not functioning as expected especially considering the age.
yes a gastro + colonoscooy will give a diagnosis which can be treated by targeted approach.
till then ask her not to lie down immediately after food, take frequent but small meals & avoid steaining at stools.
wish you good health.
Dr. Pravin Gore
Laproscopic colorectal surgeon & proctologist
Mumbai - INDIA