When you get sick with the flu or cold or other infection your muscles are contracting which means they are trying to keep your body warm.
Basically when you ave cold chills the cold chills are a result of rapid muscle contraction and relaxation which is normal during a cold or flu virus or other infections.
Although you feel chilled it's a way of your body producing heat when you're sick.
Cold chills can also sometimes be a sign of a disease known as malaria but if you have the cold or flu then it's normal for the cold chills to affect you.
The cold chills should go away within a few days to a week depending on how severe the cold or flu you have is.
Most times the cold or flu virus lasts between 7 to 14 days and all you can really do is drink plenty of fluids, rest and eat vitamin C foods and take over the counter cold or flu medicine.