"I've had something for a long time, we were trying to figure out what it was," he told the club's official website.
"It turned out I needed a root canal. So some bacteria had probably been going through my blood for some time.
"I wasn't recovering and was feeling a bit fatigued. It came to a head last Thursday when I just couldn't sleep.
"It was good to get all that figured out. I've been feeling really good since."