Can Physiotherapy Cure Numbness In The Hand Caused Due To Pernicious Anemia?

Before I was diagnosed with pernicious anaemia I had numbness in my hands and feet and since then I have been receiving the b12 injections and my numbness went away. The last time I had an injection was 3 weeks ago however the numbness has returned in one of my hands. I have been to see my GP (who is not very good, I will be changing) and she explained that it is unlikely that it is because of the pernicious anaemia because I have been having the injections so I might need to have physiotherapy but did not explain why so I would like to know why that would help?