My Brother Had A Piece Of Cancer Removed From His

my brother had a piece of cancer removed from his liver he's had a case of being cold and trembling yesterday and again today...each episode lasting 30 min to an hr....he also complained about a pain in his right side after walking a mile...he is in stage 4 cancer but had no symptoms until after the biopsy...could this be a reaction to the meds he was given at the hospital? Should I take him to the emergency room?