Hello,
On going through your complaints you may be suffering from
1) Splenic flexure syndrome
2)
Irritable bowel Syndrome (IBS)
Both have symptoms, similar to the symptoms you have. The etiology could not be located or could not found at all.
3)
Celiac disease - Almost same symptoms - it is an
autoimmune disease - specific serological test for antibobody is available.
As all imaging tests are negative, except the CT scan,
barium meal, sigmoid and Colonoscopy
The serological test can be done, along with
1) Stool culture and sensitivity - to rule out infection
2) Full blood examination, Liver function tests, Erythrocyte sedimentation rate
3) USG abdomen - to rule out gall stones and Biliary tract disease (it is already excluded by CT abdomen)
4) Endoscopy and sometime Biopsies from the jejunum
5)
Lactose intolerance - by Hydrogen breath testing
6) Estimation of calcium and vitamins especially Vitamin "D" for mal-absorption
Treatment is according to the possible diagnosis.
Mainly after consultation with a dietition - A balanced diet TOTALLY Gluten free and substituting the deficiency of iron and vitamines.
Best wishes