A middle aged lady, with background history of depression/anxiety disorder, hypertension, migraine (taking NSAIDs in a regular basic for migraine for many years), increased in body mass index, and smoker of 20 pack years history, admitted due to increasing in the severity of right iliac fossa pain for the last 3 days. Her right iliac fossa pain, started gradually 3 days ago, but the intensity of the pain was gradually increase to a rate of 8-9/10. She denied any changed of bowel habbit, with no diarrhoea or constipation, no fever or rigore. She never experienced the same pain before. On examination of her abdomen, there was tenderness over her right iliac fossa, with some rebound tendernss. Her inflmmatory marker (CRP), was elevated. Her pregnancy test was negative. An urgent CT-ABD was done, which showed no evidence of bowel perforation, with normal appendix. But, the CT-ABD scan did commented about thickening with some fat stranding around the terminal ileum and caecum area. What will be your differential diagnosis or diagnosis ??? What is the next investigation for her ??