Not related to pregnancy
Welcome to XXXXXXX
If your blood pressure is normal, headache & neck sprain
are not related to pregnancy (High blood pressure
can cause headache during pregnancy, but its rare to occur at 23 weeks).
You can rest in right OR left lateral position, which ever gives neck relaxation & reduces pain. (Though rest in left lateral position is best during pregnancy, for relief of neck pain
you can take rest in right lateral position also). You can take pillow to support neck & reduce pain. You can apply some pain killer ointment for neck pain.
Hope this helps.
Let me know if you have other concerns.