Are Calcirol Granules Advisable For Year Old Child?

Hi Dr .My son is 1 and1/2 years old. As he is a primie his milestones r slow. He learnt to sit at 1 yr. At that time his vit D3 level was 31.He is still not walking on his own and requires help. Can I give him calcirol granules once weekly for 3 weeks.