The antibacterial drugs used before or after c section may hamper the normal gut flora leading to diarrhoea. Its mainly self limiting in nature and get reduced by time. High liquid diet along with frequent sips of ors is recommended. Proper calory intake is needed at this stage as there is increased body demand. Fruits, vegetables, protein, iron containing food should be added in your diet. Again lactobacillus containing capsules can be taken to normalize normal gut physiology. You have not mentioned if there is any pain abdomen or fever. Tab metronidazole can be used in possible gut infection. But its better to avoid at this stage as it can be secreted in a small amount in breast milk. Most of the diarrhoea occurring after c sections are self limiting in nature and can be managed conservatively with proper rest and diet. Though if the symptoms increase by time you may have to visit a doctor.