Hi, Your symptoms of cold feelings throughout the body suggest an excessive amount of blood vessel constriction of your arteries and veins which will reduce blood flow to the brain, the limbs, and to the heart in general. This can account for the feelings of coldness and lightheadedness which is due to a reduction in circulating the blood volume. This automatically causes the heartrate to elevate. Constant overdrive of the sympathetic nervous system can also trigger headaches of a significant nature. You need to see a doctor who can check your thyroid gland, your adrenal glands, and evaluate you for amount and types of psychological stressors that are affecting you which can also produce these symptoms. Breathing exercises that involve slow, deep breaths with pauses during inspiration and expiration can help tremendously with the heartrate and lightheaded feelings. Also, be sure you are drinking plenty of fluids daily and not skipping meals. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Dariush Saghafi, Neurologist