I wouldn't take no more Imitrex. I couldn't take Topamax either I was having severe stomach pains when I took it.Make a journal of your headaches. Such as what you were doing when they came on,what you ate,the weather,the monthly,etc.document everything.share the info with your doctor. I have several triggers that cause my migraines such as monthly,the weather(big time) and certain foods that contain nitrites. A migraine is a vascular headache in the vessels. Have your blood pressure checked during an episode.Usually a person's BP is elevated with a migraine.try some analgesic cream on your neck. I use Biofreeze when I have a migraine because it helps to constrict the vessels back plus it may help your stiffness. Hope you find some relief I know the feeling of a terrible headache.
The thing is I have had about 20 or so CT and MRI's. I have had a couple of angiograms as well because they thought it could be a hemorrage. Topamax somewhat worked for me but made me feel real forgetful and clumsy. The doctor had a xray done on my neck because I have titanium and metal in there and he said everything was still holding in place.
I get migraines on a regular basis. I take Zomig for this condition. I tried Topamax but I had to stop because of the side effects.I was told by a doctor when I first started taking my migraine medicine if it is a true migraine the Zomig and Imitrex would help which it does within 30 minutes after taking it.I expect they are not migraines but from your injury. i would go back to the doctor and request an MRI and CT scan there may be arthritis set in from your injury.