It is important to address both the deficiencies and the weight loss. Since standard supplements haven't helped, you may need prescription-strength, high-dose Vitamin D3 (cholecalciferol) and Vitamin B12 (cyanocobalamin). If your body isn't absorbing oral supplements well, Vitamin B12 injections are often highly effective. However, rapid weight loss alongside these deficiencies suggests an underlying issue, such as a gut absorption problem (like celiac disease) or thyroid imbalance. Please consult your healthcare provider to investigate the root cause of your weight loss. They can prescribe the correct therapeutic doses of these vitamins and ensure you recover safely.