The pillow situation is a problem for many people, and those cervical pillows often make the problem much worse because your head falls into a “valley” and then a “hill” is pushing your cervical vertebrae up toward the ceiling. I really don’t like any of the pillows I’ve seen, but I’ve worked with people to fix the problem and it seems to help.
Take a hand towel and fill the “valley” in the pillow, then put the whole thing into a pillow case and turn it over so the towel is facing the mattress. Your pillow should be firm (not hard) to really support your head and prevent it from sinking down toward the mattress. Then have your pillow snuggled up to your shoulder and really feel your position to make sure your head isn’t either bent up toward the ceiling or bent down toward the mattress. Depending on the length from your neck to your shoulder (remember, your shoulder is slightly curled forward when you are lying on your side) you may need to make the pillow a bit thicker to support your head comfortably. What many people have found is that having a nice soft feather pillow works because it doesn’t give much support, but it will fill in the missing thickness and feel really comfortable.
Your pillow should be so comfortable when you lie down that you know immediately that it really fits you perfectly. It takes a bit of playing around, but it’s so well worth the effort.
Wishing you well,