What Causes Lightheaded When Driving?

I was driving and got light headed, everything kinda stopped for a few seconds so I pulled over on side of the road. Everything came back to normal after a few minutes. Two days later I get light headed again and my blood pressure spiked I went to the emergency room and they did a EKG and labs and everything came back as normal. A few days later I started getting nausea and got a head ache with pressure around my entire head and had severe neck pain / fatigue, it felt like someone was pushing on my neck. I went back to the hospital and they did two different CT scans and all came back normal, I also had a ultra sound on my heart which was normal. A few days later I have still have the head pressure, neck fatigue and now some blurry type of vision. I also went for a walk around the block and had a severe shortness of breathe and was dizzy. I am going to a neurologist in a few weeks and in for a MRI next week. Any idea? Thanks