Pulsating in abdomen

Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the strong pulsations in the abdomen having lost 25 pounds recently. You also have a history of biliary dyskinesia and anxiety.
There are few causes of abdominal pulsations and the most feared of all is abdominal aortic aneurysm which seems to have been ruled out in your case by normal abdominal CT report. The other causes of abdominal pulsations include thin abdominal wall, hypertension, high cholesterol, obesity, smoking, emphysema, intestinal obstruction etc. As far as the lower abdominal discomfort is concerned, there are no. of causes for the same including urinary retention, acute appendicitis, renal colic, pain of obstruction of small intestine which is usually peri umbilical. The radiation of pain to the lower lumbar region is common in obstruction of colon.
The symptoms of pulsations and lower abdominal discomfort might be related and may be due to subacute intestinal obstruction and the possibility if the same must be considered and ruled out. You must consult your doctor for the same.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.