Hi ! Good evening. I am Dr Shareef answering your query. Not to frighten you, but surely you should see a doctor in the nearby ER at your earliest possible. With your symptoms, we can not risk waiting till tomorrow. It could be an abdominal aortic aneurysm, but may be some other swelling from any of the intra abdominal organs is very closely related to the abdominal aorta transmitting its pulsation to the swelling. It can only be known by physical examination and further investigations. Thank you for chosing healthcaremagic forum for your health query. Wishing you all the luck and an early recovery. Dr Shareef.