I've read about prolonged PCS being caused by 'residual head pressure', I'm not sure how much I believe this but I guess bruised blood vessels could stay restricted especially tiny ones.

I went to a chiropractor but he was just just a general one, he cracked a few bones which didn't do anything (I can't believe it can be good), he also did massage which was very relaxing and showed me some neck stretches. I think gentle yoga type exercises might help, anything that manipulates the neck muscles basically.