B12 and vit d deficiency

[TheGreenNinja]

I've been found to have b12 and vitamin d deficiencies (under investigation to find out the reason why). I've had my loading dose of b12, last jab was 4/5 weeks ago and have started on vitamin d over the weekend.
I'm still completely knackered though, although some other symptoms have improved. how long should it take to feel an improvement?
I've been thoroughly blood-tested so I'm assuming those are the only deficiencies I have. I was really hoping the injections would be the answer

Vitamin B12 and vitamin D deficiencies often occur together in un- or under-treated hypothyroidism in which case ferritin and folate may also be low.

It may also be the case that you need more B12 injections than the standard NHS three months apart.

There is also a lot of difference between results coming back 'normal', which is doctorspeak for within range and being optimal.

I've had thyroid function checked and it is fine apparently. I'm being investigated to see if it's coeliac disease at the moment. I believe ferritin and folate were also checked in my blood tests. I'm (usually!) a regular blood donor so have been checked for iron-deficiency anaemia regularly and have always been fine. I'm sort of reluctant to take any further supplements while I'm in the middle of being tested, but am planning on supplementing b12 myself anyway once I get a diagnosis, with the hope that might also help