Do this at your own risk.
Lie on your front/Plank the edge of the bed. Lie your head to the left or the right depending on how you feel the muscle straining. Also you can grind your cheeks against the hard edge of the bed. You can also use this to stretch you waist / back.
Lie on your back your head against the of the bed. You can grind your neck against the hard edge of the bed. Similarly you can do this at the bathtub. You can move your shoulders blades off the bed and your head is in mid air this will bring the blood to your head.
Put a pillow behind the shoulders below the neck. This will help you to stretch your neck.