I have only just caught up with this thread, and do hope your daughter makes progress in her recovery.
About 20+ years ago now I had a nasty fall resulting in my hitting my head against a heavy fence post and shed wall (blood pressure was apparently sky high) and the fence post left quite an indentation on my forehead. I was away for the weekend celebrating my parents diamond wedding anniversary, so by the time I got home and got to see my GP my blood pressure was still extremely high, and the following day after seeing the GP I ended up with black eyes – quite scary. However nothing else showed up, then gradually little things happened, all unconnected but unexpected. The result five years later I awoke in the middle of the night and found the room spinning around me and I was falling into a permanent black hole (no street lights where I live) That was scary and the result of many tests and an MRI showed that half of my balance mechanism no longer works. Even now I wobble a lot, have given up driving as I do not like the constant turning of my head, vertical lines bother me a lot, travelling on motorways is horrible, I cannot fly or travel by train and even the TV sometimes bothers my head. I have a lump the size of a large grape that comes up in my neck and is rather painful at times, this is the result of holding my head off centre and the muscles have gone into a spasm. I have had to train my remaining balance to work for both sides, and even now some 17 years later from the balance finally giving up on one side I get caught out, and if I am not careful I end up with Vertigo and that is absolutely horrible as I cannot stand and do not wish to drop to the floor.
Obviously I am a lot older than your daughter and nothing can be done to correct my balance, but hopefully as your daughter is still quite young there is hope that given time and physio she will recover but may take time. Bangs on the head are not at all pleasant and as for concussion well that is another matter altogether.
I wish your daughter well, encourage her to takes things easy when she has to and allow her to follow her instincts – time is a great healer.