Thanks for your query.
Noted the history of chronic digestive disorders for the last 5 years, diarrhea
in the morning, blood,stool tests and colonoscopy
normal, abdominal distension, gases, Giardia cyst on previous stool tests, Doctors told you that it is IBS-D.
My thoughts after reading your history:
Get giardia treated with Metronidazole
A 5-day course of an antibiotic helps in some cases.
Take Activated charcoal
Take treatment for the anxiety
and stress if you have, this being the basis of treatment.
If all the investigations are normal, this is to be taken as IBS and treated accordingly.
Also make a list of the foods and beverages that cause the problems and stop altogether.