This is a bit of a guess too but if the patient has whiplash from the car crash, it fits. Especially as headaches are mentioned too.

Síndrome Tensional - Espacio Shantala - Coral F.F.
espacioshantala.weebly.com/siacutendrome-tensional.html
Este bloqueo ejerce una compresión del nervio suboccipital de Arnold, que emerge de entre la primera vértebra cervical y el occipital y luego recorre la cabeza ... dolor de cabeza continuo, dolor de cuello y el "crujir" de los huesos de la nuca, junto con un zumbido en los oídos, es que estamos ante un Síndrome Tensional

Síndrome tensional - Huesos y articulaciones - Todoexpertos.com
https://www.todoexpertos.com/categorias/.../sindrome-tension...
May 5, 2010 - Bueno tu diagnostico es síndrome tensional cervical y si en efecto este síndrome provoca, dolor de cabeza, mareos, vomito, vértigo y sobre todo limitación del movimiento en algunos casos.

For this I have found cervical tension syndrome/posttraumatic neck syndrome:
a syndrome of neck pain, tenderness, and spasm, often associated with ill-defined symptoms (for example, dizziness, blurred vision), resulting from neck trauma, most often of the whiplash variety. Synonym(s): cervical fibrositis, cervical tension syndrome.
Cervical tension syndrome | definition of cervical tension syndrome by ...
https://medical-dictionary.thefreedictionary.com/cervical te...
posttraumatic neck syndrome (redirected from cervical tension syndrome)

cervical tension syndrome -->
posttraumatic neck syndrome medical dictionary
<syndrome>

A clinical complex of pain, tenderness, tight neck musculature, vasomotor instability, and ill-defined symptoms such as dizziness and blurred vision as the result of trauma to the neck. Also variously termed occipital or suboccipital neuralgia or neuritis; cervical tension syndrome; cervical myospasm, myositis, or fibrositis.