It is very common to feel weak 45 days after delivery due to the physical demands of recovery and breastfeeding. Since you cannot drink milk, you can obtain calcium from alternative foods like ragi, green leafy vegetables, almonds, and sesame seeds. Along with your calcium tablet, you should consider taking an iron and folic acid supplement, as postpartum anemia is a frequent cause of fatigue. Adding a daily multivitamin with Vitamin D3 will also help. Ensure you eat a protein-rich diet with lentils, beans, and eggs. Please consult your doctor to check your hemoglobin levels and get the correct generic supplement dosages prescribed.