Medicine for B12 Deficien. Tablets?

I wanted to take a second opinion for medication prescribed by a physician. I was feeling weakness from some weeks. I did blood test and vitamin b12 test. Blood test was detected normal, but B12 was deficient (133). Doctor prescribed a course of b12 injections, which I have started. Howeve, my doubt ia on some medicines prescribed to me. I have been suggested to take Pantoprazole Sodium and Sustained Release Domperidone capsules in morning, which I think are antacids. And other medicine for vitamins has formula- 'Methyolicobalamin, calcium carbonate, calcitrol, pyridoxine HCl, zinc sulphate, folic acid" My doubt is that I read that b12 deficiency is also caused by taking antacids. So why has docter prescribed antacids alond with vitamin tablets?