Advice - Shortness of breath is now worrying me.

Wow I am sorry you are feeling so ill at the moment.How many and how frequent were your B12 loading doses?

Treatment of cobalamin deficiency

Current clinical practice within the U.K is to treat cobalamin deficiency with hydroxocobalamin in the intramuscular form outlined in the British National Formulary, BNF, 

Standard initial therapy for patients without neurological involvement is 1000 µg intramuscularly (i.m.) three times a week for two weeks, then every three months. 

The BNF advises that for Pernicious anaemia and other macrocytic anaemias patients presenting with neurological symptoms should receive 1000 µg i.m. on alternative days until there is no further improvement, then 1 mg every 2 months.

However, the GWG recommends a pragmatic approach in patients with neurological symptoms by reviewing the need for continuation of alternative day therapy after three weeks of treatmentAccording to the above highlighted paragraph you should have been on alternate day injections until there was no further improvement.  Thereafter if you have P.A. the frequency should be every two months.

Sadly it is not uncommon for symptoms to appear to get worse before they get better as the B12 starts to repair the damage done to your nervous system.

I suggest you list all your symptoms and score them on a scale of 1 to 10 on their improvement or increased severity, crossing off those which abate and adding new ones as they appear.  There is no set timeline as we are all different but at least you are on the road to recovery.

However be assured that there is life after P.A..  I've had it for 45 years and I'm still "clivealive" at 75.

Having just re-read your post I note that you are taking folic acid.  This is good and is often overlooked as folic acid is essential to process the B12 you are having injected.

As to your breathing - breathlessness or "the big sigh" is one of the many symptoms of P.A. but was P.A. the diagnosis for the chest pains that got you into hospital in the first place?

Please do not stress and worry too much in these early days of your treatment. I remember I was like a walking Zombie before I started my injections.

Could you tell us a bit more about yourself?  Do you have a family history of P.A?

I wish you well and my heart goes out to you.