@erin38 I did have cervicogenic headaches with pain on the back of my head, dizziness and vertigo, and neck pain. I had spinal cord compression because of a collapsed C5/C6 disc that had also grown bone spurs next to it pushing into my spinal cord. This was causing what is called "funicular pain" where pain is caused by the spinal cord compression anywhere in the body. That was a confusing thing for spine surgeons who missed that, but in coming to Mayo, I found a neurosurgeon who understood those symptoms. I also have thoracic outlet syndrome that is worse on one side, so it causes tightness and muscle spasms in my neck that start turning or tilting the upper cervical vertebrae. When my symptoms begin with a headache, I can lay down to put my neck on slack and feel if the alignment had changed. I worked with a physical therapist who could gently realign the vertebrae with a muscle maneuver because there are muscles that connect the neck and shoulder blade, so you can push against resistant to get it back in place. There is a big risk with instability in cervical vertebrae and no one should be working on your neck until you know if your vertebrae are slipping and by how much because that can be very dangerous if you have instability right under the skull. This should be evaluated in imaging with a doctor before physical therapy begins. I would also caution you against chiropractic adjustments because they can injure you, and that risk is higher if you have instability which is referred to as spondylolisthesis. I had 2 mm of backward slipping called retrolisthesis at C5/C6. You may want to consult a spine surgeon to look for spine issues as they can sneak up on you and cause compression, or at least get an MRI and see a spine surgeon if that report finds anything. I did have pain with my spinal cord compression, but other people have had this without a lot of pain. I had a fusion which resolved the issues, and my neck calmed down. I still have TOS and can cause a muscle spasm that twists a cervical vertebrae just a little bit, but it's very seldom and I can get it resolved easily with stretching. You may also want an evaluation for TOS, and that seems to be more common in people with whiplashes and spine injuries, so look for a specialist at a center that treats TOS. I was evaluated at Mayo for TOS as part of the workup before spine surgery. Vestibular issues can be caused by the neck and spinal alignment problems. Physical therapy can help a lot, and it can delay spine surgery for awhile by helping to maintain stability and better alignment. TOS can also affect the blood supply to the brain and cause light headedness particularly when turning the head. There is a condition called Bow Hunter's Syndrome (rare) where C1 gets twisted and stays that way affecting the blood supply to the brain because it stretches the vertebral artery that is passing through part of the vertebrae. Here is a link with a lot of detailed information.
This page has several articles able vestibular issues, TOS, and problems associated with the atlas and axis ( C1 & C2)
https://mskneurology.com/category/jaw-head-neck/