So I finally had my consult ('second opinion') in Leuven (Belgium) at the gastroenterology unit of the university hospital, after I did see a specialist at the gastroenterology unit of the university hospital in Groningen (The Netherlands) beginning this year.
The specialist I spoke with also doesn't think that my bowel problems, chronic constipation, in my right lower abdomen, is caused by pseudo-obstruction (CIPO).
Therefore, the first working diagnosis from 2019 still stands, a functional bowel disorder (FGID) leading to chronic constipation in the first part of the colon, the ceacum in my case. I think the nowadays more appropriate naming is a disorder of the gut-brain interaction.
I told the specialistg in Leuven that I use bisacodyl 5mg, 3-4 times daily to keep the chyme/bowel content flowing. He said that I should better use linaclotide, a secretagogue (Constella/Linzess) (better transit/may lower abdominal pain/stimulates secretion of chloride/bicarbonate/water into the intestinal lumen) on a daily basis and maybe 1-3 times during the week bisacodyl 5mg, if still necessary.
Unfortunately linaclotide is only available in one dose, 290mcg capsules in the Netherlands. After my consult with a GP and the pharmacist yesterday, I will try to open the capsule and divide the content over smaller capsules so I can start with a somewhat lower dose.
Lower dosages than 290mcg linaclotide (145mcg and 72mcg) for chronic constipation have already been approved by the FDA in the USA.