What other assessments should be included for this patient?

Kevin Valeri is a 64-year-old man who presents to the gastroenterologist’s office with constipation and abdominal bloating.
Subjective Data
Pain level is a 4/10 location = right lower abdomen
Retired Engineer
States he has been going to the bathroom with the help of laxatives, but not having regular movements
Appetite is decreased, some nausea
PMH: depression, anxiety, chronic constipation
Objective Data
Vital signs: T 37 degrees Centigrade, P 64, R 16, BP 124/58
Bowel sounds hypoactive in all four quadrants
Medications: Lamictal 200mg daily, Lexapro 10 mg daily
Weight = 210 lbs, last visit weight = 195
What other assessments should be included for this patient?
What questions should the nurse ask with regard to the abdominal pain?
From the readings, subjective data, and objective data, what is the most probable cause of the abdominal pain?
What should be included in the plan of care?
What interventions should be included in the plan of care for this patient?