Hi Bramble
I see you are based in Scotland. I know of a practitioner in Braco who does this - I attended her personally. She generally works with mineral deficiencies. It was expensive to get the range I needed but they did help.
I have also attended someone in Inverness who also tests hair, although does not deal with vitamins. She works with vibrational medicine.
I have found both really very helpful Bramble and I hope you feel better soon although generally you are likely to have to take them for around 3 months to experience the improvement.
Fx