Vitamin B12 Deficiency, Staggering Walk, Bleeding In Mouth, Exhausted, Numbness. Taking Injections Every Three Months And Nasal Spray. Solution?

I have vitamin B12 deficiency and have injections every 3 months. I have nerve sensation loss permanently in my hands and feet, I stagger when I walk. I have a burning sensation down my side and II cannot control my body temperature I oscillate from freezing so much I am shaking to feeling so hot I am burning and cannot breathe- I become very breathless in these bouts. I am now completely urine incontinent. I feel better after about a week after the injection. A further 2weeks later and all the symptoms are back again and after 6 weeks from the injection I am back to staggering, bleeding in my mouth, feeling absolutely exhausted, so tired I just feel I need to be on the floor and tearful which has never been me. I want nasal spray to keep up my levels between injections. My GP says the regime is once every 3 months- one size cannot fit all. The numbness is worsening it is now up my arms and my knees. No one is listening. I was normal last summer. I am now virtually disabled. I have found a nasal spray in the US but it is licenced only for those without nerve damage involvement.
Can I safely use this spray. I cannot go on any longer without some kind of help.