Your
B12 of 116 is a genuine deficiency and is very likely the main reason you feel drained -
vitamin D at 20.4 is only mildly low and adds to it. Standard correction is vitamin D 60,000 IU once a week for 8 weeks, then monthly, along with B12 replacement (injections work faster at this level, oral 1500 mcg daily is the alternative), plus
calcium in the diet. Recheck both after 3 months. Since you are on Concor, remember that beta blockers themselves can cause tiredness, so I would also want your haemoglobin and
TSH checked before blaming vitamins alone. Book a consult with me on Practo and I will put you on the correct dosing schedule.