My Daughter 34 Yr Old Just Diagnosed With Critical B12

My daughter 34 yr old just diagnosed with critical B12 deficiency her level is 117 . She is not vegetarian eats meat 3 times a week. No symptoms no infertility, occ. fatigue but mother to 2 and 4 yr old and works 50 hrs a week in successful career. Given her first B12 injection but she is in disbelief. Plan is weekly injections and repeat in 4 week . If no improvement a colonoscopy. What do you think of the plan?