Hey, Beelzebore92 we both have skateboard injuries, I had two head impacts in my late teens which only now I'm beginning to realise had an effect on me.

I think your problem is rooted in anxiety, the common PCS symptom to nearly all concussions. That is why you are waking with clenched teeth and having trouble getting your breath. Yawning cools the brain so I would guess the neck inflammation is restricting blood flow somehow. I would make sure you keep good posture and not be slumped over a computer like I am at the moment. Gentle neck exercises might help but go easy.

Some on here, including me, have found relief in meditation and deep breathing exercises, basically taking yourself out of your situation and giving your brain time to empty itself of thoughts. Normally we spend a fair bit of time thinking of nothing, our brain just idling, PCS makes us think/worry constantly and it tires the brain.