Hello, I couldn't tell you if it is lack of medications, but I had the same experience a while back. I was so afraid of driving or even being in a car with anyone who was driving. Once I got my meds under control, I was OK. Personally, I think the Buspar the pdoc put me on is what gave me the anxiety of driving. It didn't help it. Once I stopped taking it, I was fine.
I take a total of 4 meds now. Now I love to drive. I even want to take my car to the racetrack.
I hope you can talk to your doc about it to get your anxitey under control. I know how awful it can be.