My 99 year old mother, who lives with my sister,
Has her GI tract/digestive system deteriorated or regressed to the point where she will alternate between constipation and explosive bowel movements? Should we take her to a GI specialist? Given her immobility, can anything really help?
There may still be remedies
I am sorry to hear about your mother's troubles. Being completely immobilized carries many issues as you point out, and alternating diarrhea and constipation is not uncommon. I suggest a high fibre diet as you mention, as this tends to solidify the stools without causing or exacerbating constipation. Furthermore, I advise you to see a gastroenterologist or a colorectal surgeon, as surgery with a permanent stomach may be a solution, unless your mother is very ill and fragile.
Hope this helps. Please let me know if you have further questions.