Pain is the base of the skull can be tough to deal with. The muscles in the back at the base of the skull are called the occipital. In the case of forward head posture (the most common postural misalignment), the occipital muscles get pulled on. Because these muscles are constantly being pulled, they are always tensioned and have trigger points.
Let's first go over a good way to relax the muscles and release trigger points(knots in the muscle).
Place both hands over ears, thumbs land on occipital muscles. These muscles are located at the base of the skull. The left thumb hit the left occipital and the right thumb hits the right side. Dig those thumbs in, breaking up the trigger points. You can also massage the area moving those fingers in a circular motion.
You can also use a muscle relaxing gel like 'Biofreeze'. It works well and allows you to massage those spots without getting any skin burn.
Next, knowing that the occipital muscles travel from the base of the head to the first couple spinal segments, flexing the head will stretch them a bit.
Try flexing the head while stripping the muscle (run your fingers down the muscle superior to inferior). In other words, top to bottom. This allows you to roll over those knots in the muscles. This is often referred to as "stripping" the muscle.
One really cool thing is that you can do this anywhere or anytime. You can do it in shower as well, because you can use soap like a gel. Get a good lather and this will help reduce friction too.
2 - Biofreeze Gel
3 - Google +