A year ago my neck pain was getting bad enough that I despaired of ever riding a diamond frame bike again. I tinkered with recumbency, but I didn't see a recumbent bike filling all the roles my diamond frame bikes do. Besides not being able to turn my head to sightsee on the bike, I also had difficulty turning my head to check blind spots while driving. Today, the road bike feels like the most natural conveyance in the world and I even went for a century ride a few weeks ago. To get from then to now, I:
Visited my doctor and got a Rx for Physical Therapy. My PT knows I'm a compliant patient and after diagnosing the problem (mainly bad neck posture) he gave me a set of exercises to do at home.
A previous trainer referred me to:
https://www.amazon.com/Treat-Your-Own-Neck-803-5/dp/0987650416 and:
https://www.amazon.com/Treat-Your-Back-Robin-McKenzie/dp/0987650408I can't recommend these books highly enough. Cheap, a quick read, and a specific plan to cure what ails you. They kind of expanded on what my PT offered and give you a framework for making things better.
I have a personal trainer who carves out weight workouts for me. She was a real find, with a recent Masters in Kinesiology and a bike racer to boot. She designed a workout with neck specific exercises. On that recent century, I did have to stop a few times to get my neck stretched out and I basically ran through the workout's neck stretches and exercises. Having a trainer is great, but you have to find one that is capable of and inclined to help you with your goals. A previous trainer, also a bike racer, made me way faster on the bike (a goal at the time) but was prone to breaking things.
On the recommendation of the Mckenzie books, I now sleep with a cervical roll and a thin pillow and have lumbar rolls for my car and office chair.
Of course, the human condition is vastly variable, and my success may not predict yours (YMMV). I had the good fortune of not having any underlying issues other than old age and bad posture.