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Detailed Answer:
I read your question carefully and I understand your concern.

There can be different causes to vomiting and dizziness. An ear related cause like BPPV is the most common one. If you refer to the Epley maneuver I do not think a self applied test is valid to exclude it. I am not sure you have understood it right, there is no fluttering of the eyelid, there is nystagmus which is a movement of the eyeball itself. I do not think one can confidently observe that himself, it should be done by your physician or even better an ENT doctor. Afterwards if that is thought to be the case you can perform the maneuver at home, but the testing for the affected side and the first maneuvers should be done by a physician.

Among other possibilities to exclude would be blood pressure fluctuations. Bot high and low blood pressure may produce such symptoms. So blood pressure measurements both supine and standing are needed during these periods.

Narrowing of the neck vessels could be another cause to consider, most commonly due to atherosclerotic plaques. Narrowing of the vertebral arteries could lead to episodes of drop of blood flow to the posterior part of the brain which could manifest with dizziness and vomiting. So a cheap quick exam such as Doppler ultrasound or preferably an Angio CT or Angio MRI could be considered if there are no ear or blood pressure related causes found.

Neck arthritis can also at times present with such symptoms when involving upper neck levels as it leads to compression of the upper cervical nerves which convey information on head and neck position and are thus involved in balance.

As for treatment of course it depends on the cause. I would use an antihistamine like Meclizine or Dimenhydrinate to alleviate the symptoms, but in the meanwhile would start investigating for the cause as other treatments would be necessary in the case of a blood circulation related cause.

I remain at your disposal for other questions.

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Detailed Answer:
The fact that you have had a neck injury makes you someone more prone to neck issues. The C7 is in the lower part but usually spinal issues are not isolated, issues at one level may lead to instability and degenerative changes at other levels. It happens in many people with age, the traumatic event makes the changes of such chronic degenerative changes higher.

As for what to look for to know if you have such spinal issues the most common symptoms are neck pain often radiating to the back of the head and episodes of neck stiffness. Other symptoms depend on the affected levels, as I said upper levels may cause dizziness, lower levels may also produce pain or abnormal sensations spreading to one limb in the area covered by the compressed nerves. Tests to evidence such spinal changes may range from the cheap x-ray to the MRI being the best test.

Let me know if I can further assist you.

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