One of my patients had jaundice, viral hepatitis A, but his bilirubin was returning to normal slowly. After Two months it was not tolerable for pt, got admitted in hospital under GI surgeon, due to a bulky pancreas in USG. CECT and cholangiogram were done, it showed the BIG head of pancreas with some swelling over that, decided to operate in the mind of CA pan.

They opened abdomen and close after inspection. The patient is still alive with me. What is the most probable diagnosis?