The source of the depersonalisation (if it actually is that) could be one of a few things from what I have read:

1) hormonal imbalance
2) reduced blood flow to brain
3) temporary swelling due to concussion
4) brain damage

All of these, I assume, could cause a variation in the way in which particular brain waves are sent, travel, or read, which could be the source of this current feeling. I hope its the 3rd one and eventually subsides.

It's very difficult to get any clear answers as it's all done with external tests.

Upper cervical chiropractic or osteopathic therapy could be the way to go as a start and I'm currently looking into where to get this service locally.

I've started on B-12 supplements alongside omega-3 and multi-vitamins which will hopefully aid recovery. I will add additional supplements as necessary but am cautious about loading up in one go to ensure that there are no reactions.

The next stage would be to review the possibility of a hormonal imbalance as a result of the concussion - and how this could be assessed and treated if it was to be the source.