My mother had throat cancer. Had the cancer removed, had a stroke 12 hours later at home, recovered her speech and mobility within 24 hours, thank God. However they put her on antibiotics for pneumonia, developed c-diff in the hospital, went home improved on antibiotics, c-diff infection returned during her chemo, and she died of sepsis. Long story short, a virulent infection, not fully treated or not responding to treatment can cause septicemia especially when in a weakened condition.