Updated 09/24/14 – 6:05 p.m.

CHICAGO (CBS) — Suffering from an infection related to his cancer treatment, Francis Cardinal George has canceled several public appearances since Saturday.

CBS 2’s Susanna Song reports the cardinal had to back out of a speaking engagement Wednesday morning in Mundelein, though he planned to resume his regular appointments in private on Wednesday afternoon. A spokeswoman for the Roman Catholic Archdiocese of Chicago said George also planned to attend the Catholic Extension Society’s dinner in Lincolnshire on Wednesday, though he has canceled an out-of-town trip later this week, after doctors advised him not to fly due to the infection.

Cardinal George is battling an infection in his right foot called cellulitis. The infection appears to be a side effect of the experimental medication George has been taking for his bout with kidney cancer.

The Archdiocese said the cardinal has been taking antibiotics and resting to fight off the infection. That explains why, after introducing his successor – Bishop Blase Cupich of Spokane, Washington – the cardinal has canceled all other public events.

He was scheduled to present a paper in Washington, D.C., this week, but doctors advised him not to fly because of the health risk from his infection.

Tuesday night, George was scheduled to attend an awards dinner at St. Joseph College Seminary, but had to cancel. Cupich attended in his place.

Earlier this month, CBS 2 Chief Correspondent Jay Levine spoke to a doctor about the experimental drug the cardinal has been taking to help him fight the cancer in his kidney.

“Traditional chemotherapy’s abilities to shrink tumors is somewhere around 10 percent, whereas in this therapy, earlier studies showed 45 to 50 percent,” said Dr. Russell Szmulewitz with the University of Chicago Hospital.

That drug might have led to the cardinal’s infection.