Delay in treatment??

I have received my blood test results I have been told I'm deficient in B12.  The doctors have told me I need a course of injections but the earliest they can book me in for these is 2 weeks.  I'm curious to know if this time delay for treatment is acceptable.

I am finding daily life a struggle, tiredness, feeling dizzy and faint.  I have previously had a B12 deficiency and also suffer from stomach cramps, feeling bloated and severe heartburn (I am on stomach pills and also go through a bottle of gaviscon every 3 weeks).

Any helpful comments would be much appreciated.