from the way you describe it it sounds impossible for that type of injury to give you those symptoms. moreover it should have caused the symptoms at the time and then regress, not the other way around.
In my opinion something totally distinct is happening to you. if you include lack of memory (short memory?) and brain fog then it rules out cervical injury completely.
I had similar symptoms which I believe started after some sort of infection viral or whatever. at some stage it affected my heart too, slowing down the heart beat at night, it would get better after a couple of hours being up in the morning. did you check your heart beat rate?
what type of nerve study was conducted? what type of impact on the nerves? it would take a pretty large spinal disc herniation to cause that.
did you have full blood count? when did it all begin, except for the pain in the neck? do you remember anything unusual preceding the symptoms?
I had the same symptoms, due to Menopause! if you are in your 40 or 50's, that could be it, along with possible low thyroid and adrenal issues. I would go see a hormone doctor that specializes in bio-identicals and he can definitely test your hormones and thyroid. I went through hell feeling like you did for a year until I saw one, now I take a dessicated thyroid pill and some hormone creams, very small dose, but I have no pains or stiffness, no more debilitating fatigue and soon will be back at work. I am 51
Labile hypertension (fluctuating hypertension) may be due to hyperthyroidism, renovascular hypertension, seizure disorder, migraine, alcohol withdrawal, carcinoid syndrome, panic disorder, baroreflex failure, or drugs such as cocaine, amphetamines, or clozapine. Considering your history of neck injury, baroreflex failure is the most likely diagnosis.
From the Rare Diseases Network website..
"What is Baroreflex Failure?
Baroreflex Failure is a rare disorder characterized by change of blood pressure with episodes of severe hypertension (high blood pressure). There can be increased heart rate during stress and hypotension (low blood pressure) with normal or reduced heart rate during rest.
Symptoms may include:
Headache
Excessive sweating
Extremely high or volatile blood pressure and heart rate with spikes in blood pressure in response to stress, with periods of normal or even low blood pressure during rest.
Heart rate that does not respond to medications intended to improve it
Note that Baroreflex Failure may resemble another rare disorder called pheochromocytoma, a catecholamine-secreting tumor.
What causes Baroreflex Failure?
Possible causes may include:
Surgery and radiation for cancer of the throat
Injury to glossopharyngeal and vagus nerves (nerves involved in sensing blood pressure)
Cell loss on both sides in the nuclei of the solitary tract (NTS, a column of cells located in the medulla) in the setting of a degenerative neurologic disease of the brain.
For many patients, the cause of Baroreflex Failure is not known.
How is Baroreflex Failure diagnosed?
Baroreflex Failure resembles other more common disorders, so its diagnosis is challenging.
In addition to asking detailed questions about the patient’s health and family history, the physician will conduct a physical examination, which will include checking blood pressure and heart rate in specific circumstances, such as during daily activity and with medication challenges.
What is the treatment for Baroreflex Failure?
Treatment for Baroreflex Failure involves medications to control blood pressure and heart rate and to reduce stress."