Hello Elle.
Sorry to hear about your hair loss as this tends to be very anxiety provoking (for women especially).
There can be many reasons for hair loss including gut problems, but anaemia is likely to be the root-cause if that is a condition you already have.
My mother suffered from Pernicious Anaemia: and lost almost all her hair. The recommended treatment nowadays seems to be vitamin B12 injections.
I would recommend you look on the pernicious anaemia society website for lots more information.(I'm sure there are many other useful websites covering this issue).
Best wishes
Bill