My doctor has prescribed a 9-day course of prednisone, which I am scared to try because it is supposed to cause sleeplessness and anxiety. I have struggled with both those things but now seem to have both in better control. I would hate to go backwards and have those symptoms again. Are there any positive or negative experiences with using Prednisone to break the cycle of chronic headache?

That is a regular course of action to break what they call a "cluster" headache. It is a common treatment for anyone who gets them.
The first day is the highest dose and goes down from there. Every person reacts differently to it so it is hard to say.

Myself I have no side effects from that amt.
I have had hot flashes and cold sweats from higher dosages given to me for my lupus and for months at a time. If you are a coffee, tea, coke drinker stay away from it while you are on it and maybe that will help with both.

Actually a few weeks ago I finished a "medrol dose pack" same thing, but was only seven days.

I did 3 stints of this after my injury and they did not help with headache. Have you been dx with headache tbi or cervical injury or all 3?

My diagnosis as of now is Post Concussive syndrome, chronic headache, Depression, Nonspecific

This may change after further tests - another MRI and lumbar puncture - and appt with headache specialist. Nothing has ever been said about my neck and I have emailed my doctor to ask about this after joining this forum and seeing that so many people have neck involvement. I was in a car crash, so this is a possibility for me.