A stiff neck results from slowed circulation and lymph flow to muscle tissues. Use contrast hydrotherapy—a quick blast of hot, then cold water—to get the blood pumping again. In the shower, first run hot water over your neck for 20 seconds to increase blood flow, then switch to cold for 10 seconds to constrict blood flow. Alternate three times, always ending with cold. When you get out of the shower, your body will send the blood back out to the skin, which results in a final dilation of blood vessels and—voilà!—a looser neck.
My wife is an M.D. trained in pharmaceutical medicine. She prescribes drugs every day, but also recommends medicinal herbs. In our medicine cabinet, we stock drugs and herbs, but we use more of the latter. When we catch colds, we prefer echinacea and andrographis (immune-boosting herbs proven to speed recovery), ginseng (ditto), licorice root (for sore throat), tea or coffee (caffeine helps relieve stuffed nose and chest congestion), eucalyptus lozenges (for cough), and pelargonium (if post-cold bronchitis develops).
You put a salt and warm water mixture in something that looks like a little teapot. Then pour it through one nostril and let it drain out the other. You have to practice a little, but once you get the hang of it, it can ease allergy or cold symptoms and may even help you get rid of a cold quicker. Just make sure you use distilled or cooled boiled water and keep your neti pot clean.