Barium is not a very good test to diagnose ulcerative colitis
. In view of your symptoms i suggest that you consult your doctor and get a rectal exam and a sigmoid scopy done.
Itching in anus could be due ti worm incfection, Skin infection
, Fissure and piles or inflammatory bowel disease
. The above two tests will help to find the cause of the problem and rule in/out the conditions mentioned above.
Hope this helps
Do get back in case you have further queries
Dr Samir Patil