Welcome to Healthcare Magic.
I appreciate your efforts for medical consultation in so much distress.
Well, its already 4 days since surgery and presence of pain with not passing stools clearly directs the cause towards constipation
, and as you were taking codeine
as pain killer it also contributes to constipation.
Now coming to relieve this, I think you should start taking laxatives and if not relieved than dulcolax
suppository may be required
Wish you good health.