My Husband Had Surgery Last Wednesday. The Removed His Left

My husband had surgery last wednesday. The removed his left upper lung. Today he had a horrible pain attach which he describes in his left side up to the middle of his chest. Would this have to do with the surgery or just maybe a reaction to the medication, hard on his stomach? He is still down with the pain saying it is a little better (about 1 hour now). He has gone from the sweats to the chills, he was totally white but is laying down and I can't really tell if that has changed too much.