Toews said his body "just fell apart."
"My immune system was reacting to everything I did, any kind of stress, anything I would do throughout the day it was always kind of that stress response," Toews said.
He thanked Hawks fans and his teammates for their support and he said he's ready to get back to the ice and play.
Toews, 33, has played 13 seasons with the Blackhawks, including three Stanley Cup championships. He missed all of last season after disclosing he was suffering from an undisclosed illness.