I think you are right about the brain jarring from the foot pounding. Try running or walking with foam ear plugs in. You will hear the pounding as it impacts your brain.

The CT is not going to help unless you have serious head aches and /or a loss of motor control like a stroke would cause.

You do not want CT radiation on your brain if you can avoid it.

How's your neck, specifically your upper neck ?

Have you tried icing your upper neck and back of your head when you get a head ache ?

Have you read the vitamins sticky at the top of this forum ?

When you are out of breath, try to notice if you have been holding your gut tense and holding your breath. This can be a problem with PCS.

I have had a lot of struggle with breathing since my mTBI in 2001. Being aware of breathing can be a help.

My best to you.