http://orthopedics.about.com/od/cast...ht/quickly.htm

If the sling has a knot or a clasp, make sure it isn't at the center back of your neck, but off to the side where it doesn't connect to your neck. Having it at your neck can cause headaches and neckaches. If the strap is too narrow for comfort, try using one of the car seatbelt cushy covers.