With the help of gravity, your eyes, ears and feet conspire to give you neck and shoulder pain.
One thing your brain insists on is placing your eyes on the horizon, so you can look straight forward and know with confidence that structures looking upright are in fact upright (or very close to upright). The brain does that with the aid of gravity and your inner ear balance tubes. Fluid in these tubes moves as a result of you changing your head position and gravity, so your brain can keep track of the gravity forces and your head's relative position.
The feet are the trouble makers. It is actually your feet combined with standing and walking on flat surfaces. As you have read throughout this website, excessive pronation of the feet will distort your posture, and if you look around, you will quickly realize that most people carry their heads significantly forward of their spine. If you naturally move your head forward, you'll be looking down. Walking that way may help you fin treasures on the ground, but it won't get you to where you want to go, so your brain will insist on placing your eyes on the horizon, and that requires you to lift your head, meaning all the muscles in your neck, particularly the back and side of your neck. Consider your high shoulder on one side also influences the nuscle tension to level your head. Your head is heavy, and for every inch your head moves forward of the spine, it doubles the load on the muscles supporting it.
Correcting your posture to specifically avoid your head forward position and unlevel shoulders will stop you from contorting your neck. This quick self assessment will demonstrate if your feet can be the source of your neck and shoulder pain.