Nursing Diagnose for post-op

Ok, here is the scenario, 56 yr old male with a hx of diabetes mellitus Type 2 and peripheral vascular disease. He is overweight at 5'6" weighing 280 pounds. Admitted for a bowel obstruction and is now on the unit 12 hrs post-op from right hemicolectomy. There is a nasogastric tube set at low intermittent suction. There is also a Davol drain inserted near the incision with moderate amount of sanguinous drainage. His Foley catheter has clear, yellow urine and the amount has been averaging 50 ml per hour. His IV in the right forearm is Lactated Ringers running at 125 ml/hr. The Abdominal dressing is clean, dry an intact. Patient is complaining of incisional pain at 6 out of 10.

I'm not asking to have my assignment done for me, I wouldn't learn that way but where to I start? Pain, I don't know what to focus in on. Any advice would be great.

Thanks