Anxiety and medication can also cause chills, as well as sweats. If it turns out you aren't ill with anything, do you exercise at all? In other words, are you circulating your blood? Humans are built to move, not sit still. There are also warming herbs that can help circulate the blood, including cinnamon, though that will lower your blood sugar so if low blood sugar is the problem this isn't for you, tumeric, cayenne, and the like.