Except for the entire head twitching, possibly this comes from computer use. If you are right-handed, you can get something similar to carpal-tunnel syndrome from being on the keyboard a lot, that doesn't hit your wrists but instead the upper shoulder and neck. Do you have any arm support when you're sitting and working online? You might try putting a pillow on your armrest of your chair to raise your arm into a new position when working on a keyboard or with a mouse, and see if it changes where it hurts. As far as the head twitching, it could come from the same thing if you have inflamed muscles that are pinching a nerve in your neck.