Good Luck, I really hope the blood work shows up dome answers & treatment soon!
Your comment on radiation might be relevant as Ive read that can deplete B12 levels, it did for a friend of mine. Hoping the blood results make diagnosis easy, though perhaps don't rule it out if bloods are "in range" & you can relate to the symptoms lists I posted. My own daughters level was 412, lots of things can skew the blood tests results, plus they are not reliable, so they are meant to treat on symptoms, not blood results, as its a harmless, water soluble vitamin, so cannot harm, but can do a lot of good.
We managed to get a "therapeutic trial" for our daughter in the end. After over 18 months in screaming pain, stuck in a wheelchair (on a good day) unable to sleep for more than 2 hours, sensory processing so bad she couldn't even bare her room light on as it made too much noise, anxiety & phobias, headaches & much more - first injection her tinnitus stopped & she slept a full 8 hours for the first time ever, by the 6th injection she was walking again & her pain was 90% gone & no more headaches & big improvement in anxiety too.
She is also hypermobile & has a diagnosis of "Ehlers Danlos Hypermobility"too, but the symptoms of that have improved massively with B12 injections too, they are linked conditions.
If the doctors don't find any other answers, then the group I mention below might be good for you to join anyway. They are a worldwide organisation, run by people in several countries & will have members, if not admin where you are. They will be able to help with the system local to you & how best to get treatment, plus what else your DD needs to take in order for the B12 to work properly
Keeping everything crossed for you, enjoy your time back at hime & hope you manage to get some much needed rest 

