I have taken many MRIs (with and without contrast) after my mild Traumatic Brain Injury and diagnosed with Post Concussion Syndrome. Faced no problems with contrast. Very rarely I heard people cannot tolerate the contrast. Some labs do a Creatine (?) test before giving contrast. You can ask your lab about that.
I have been suffering with Post Concussion Syndrome for 2+ years now. Headaches, nausea, dizziness, fatigue etc., and my symptoms got worse only after 5 weeks. Most likely you are suffering from PCS and it takes its own time. There are so many therapies/meds etc., you can try to get relief and I am still trying and is a long story.......Most recover quickly (in 6 months) and only some unlucky ones suffer a long time. After 1 year seems like you cannot set a time line.
I doubt MRI will show anything at all related concussion at this stage if CT scans are negative. But if your doctor wants to rule any other condition then go ahead and do it.
Welcome to the MedHelp forum!
Well, yes there will be horror stories of contrast creating reactions, but they are not co common. An average man usually can undergo the contrast MRI without any side effects. Also, it provides very useful information about the brain structures, tumors, infarcts etc which could be missed on simple/plain MRI.
Headaches after a brain injury can also be due to concussion, and normally CT and MRI are normal. However, yes, MRI should be done to rule out brain injury as the cause. Stress due to concussion and brain injury can also be the cause. Also get your blood pressure checked. Take care!