There can be several other causes like hypothyroidism, liver diseases, low Vit B12, adrenal insufficiency, liver failure and as a side effect of
some drugs. Chills are also felt when a fever is about to start in case of
malaria and bacterial infections due to release of toxins. One can also feel chilled if you are about to break into viral fever. Vit B12 deficiency causes feeling cold, tiredness, dizziness etc.