Please do not reuse leftover cefpodoxime proxetil or start any new antibiotics without a doctor?s evaluation. Watery diarrhea is often viral, and inappropriate antibiotics can worsen it. Since you started metronidazole and zinc yesterday, it can take 48 to 72 hours to see improvement. Please continue giving oral rehydration salts (ORS) and zinc to prevent dehydration, which is the most critical step. Keep offering small, frequent sips of fluids. If your child develops danger signs like extreme lethargy, persistent vomiting, high fever, or blood in the stool, please visit a pediatrician immediately for a proper physical examination.