Like others here, driving over a pothole or nodding too quickly can cause me to relapse. Your brain probably doesn't like jarring. For now, you might want to forget the running and get a stationery bike.

It may also be that cardio exercises, like running, increase you heart rate and trigger your headaches. I have to wear a monitor while working out to keep my heart in my PCS safe range.

I know it's frustrating, but you're lucky that you're able to exercise as vigourously as you do. Congratulations too on the extent of your recovery. Your story gives me hope.

Cheers