Had a ruptured appendix many years ago. The surgeon explained that he removed 12 inches of my small intestine and a fist size piece of large intestine. That's the only explanation I got. Went on with my life feeling mostly normal. After 20+ years I started having some issues. Uncomfortable stomach and bowel issues, not real serious, not all the time.
They slowly became more noticeable and about 10 years ago I ended up seriously anemic. The doctor had no clue, but I researched and found out the last 18 inches of your ileocecal is where B12 is absorbed and I had most of mine hacked out. Started taking B12 twice a day and my anemia went away. Then I figured out I had no ileocecal valve to stop backflow from my acending colon back into my small intestine. So I always have small intestinal bacterial overgrowth, which causes IBS and probably Crohn's disease. Three different doctors pretty much flat out ignored me and didn't offer much help.
I do the best I can, some days are OK, others kind of miserable. I have experimented and learned several tricks which help. One of these is drinking lots of water, which may help people with IBS. Another is to keep a rigid schedule on eating and going to the bathroom always at the same time. Of course a careful diet helps, but not always the same for all people.
I don't know how, but while my schedule is pretty limiting I have managed to stay mostly functional. Working out, running and riding my bike always helps me feel better. I am just trying to stay positive and make the best of things, no point in giving in or giving up to become totally miserable. Not happening...