Yes, Septran (co-trimoxazole) can help clear up the diarrhea if it is caused by a bacterial infection, especially since the probiotic (Gnorm) and zinc (Z & D drops) have not resolved it. Please give this medication exactly as your pediatrician directed. Alongside this, keeping your 4-month-old hydrated is key; continue frequent breastfeeds or formula, and offer oral rehydration solutions (ORS). Please seek immediate medical care if you notice signs of dehydration, such as dry mouth or fewer wet diapers.

It is reassuring that your symptoms are improving. To safely resolve the remaining loose motions, you can take a probiotic supplement containing Saccharomyces boulardii or Lactobacillus to restore your gut flora after antibiotic use. Avoid anti-diarrheal medicines like loperamide unless specifically prescribed by your doctor. Since you are diabetic, you can use Oral Rehydration Salts (ORS) for hydration, but monitor your blood glucose levels closely as ORS contains glucose. Stick to a bland diet like rice and yoghurt, and consult your treating physician to ensure your blood sugar remains stable and to check if your diabetes medications need temporary adjustment.