My dad used to get the chills as well and they seem to be quite common. And there are a ton of posts here on the website about them and if you use the search function then I know that you will be abe to read lots on them. My dad never had chemo so we couldn't put his chills down to that, and unlike Lainy and Teddy, my dad never had the chills with a temperature or an infection so we couldn't put them down to an infection of any kind. They just used to come out of nowhere and would last for a short amount of time, then they would just pass as quickly as they had come on. It was quite frightening at first, especially as we didn't know what was causing them. But then my dad sort of got used to them and knew that they would go away after a bit. Hope some of that helps.
Any advice or comments I give are based on personal experiences and knowledge and are my opinions only, they are not to be substituted for professional medical advice. Please seek professional advice from a qualified doctor or medical professional.