If MRCP has already been performed for the diagnosis [if not then it should be done first], best is to perform a sphincterotomy to open up the choledochus followed by stenting. If cholangitis is bad then initially a nasobiliary drain may be put in for lavaging the bile duct for 3-4 days before stenting. IV antibiotics like meropenem or piperacillin + tazobactam is a must for about a week. Serum CA 19-9 level may be estimated if malignancy is a concern.
Welcome sir, cover with broad spectrum antibiotic covering anaerobic infections + the obstruction should be drained and investigated for the probability of malignancy.