The common causes, which are associated with Chills are-
Insufficient protection from cold temperature or weather.
Age- newborns and elders (like you) are intolerant of cold temperature.
Stress or poor health condition.
Malnutrition and poor diet or B-complex vitamin deficiency
You should follow these tips-
You should Limit alcohol and caffeine intake and remain away from smoking tobacco products as they increase cold intolerance.
If you have deficiency to B-Complex than you may be sensitive to cold and have chills,so take b-complex therapy.
You should Drink warm tea,and hot drinks.
You should try to have room temperature warm.
I suggest, you to make an appointment with doctor, so that cause is evaluated, and you get appropriate management. take care