Welcome to HealingWell!
Have you thought about calcium treatment for your D? Here is a post from lnape about using calcium to control you D: Calcium info
It is a long post but well worth it. Many here on the site take calcium - it helps soothe an inflamed gut, and it binds your stool.
Have you been tested for Celiacs? During the colonoscopy did they take biopsies? Did your doc send blood to an IBD specialist (here in the US many docs use Prometheus Laboratories)?
Co-Moderator for the IBS Forum