Kaiser can be somewhat difficult to negotiate to find the right physician to help. They do take your problem seriously as they authorized an MRI and MRA which are not inexpensive tests.
I am not sure what “very compressed” C4-7 vertebrae mean. Are the discs compressed or the spinal cord or the nerve roots? C1 cannot slide off of C2 unless the transverse ligament is disrupted. It is unlikely that you have that condition.
See the section regarding “how to describe symptoms” to fully explain your symptoms.
Dr. Corenman