What Does Hypertension With Basal Ganglia Calcification Mean?

I was transported recently to the emergency room after a car accident. Attending er doctor diagnosed my injuries as a head injury and shoulder concussion. When my BP was checked, it was 166/94 upon arrival. At discharge, my BP had returned to normal.
Six weeks later, as I am under several doctors care, I have verbalized complaints of severe headaches which has become more pronounced recently.
A few days ago, I again returned to the emergency room with an extremely explosive headache and a BP of 196/126. I was diagnosed with hypertension and HA headache. No previous history of headaches or high BP. I am 49 years old, jog 5-8 miles daily, African-American and is considered to be in the best physical shape of my life. Additionally, the er doctor ordered a CT which revealed basal ganglia calcification.
What is going on?