To give the Econorm (Saccharomyces boulardii) sachet to your 7-month-old, mix the powder into a small amount of lukewarm water, breast milk, or formula. Avoid mixing it with very hot or very cold liquids, as this can make the beneficial yeast less effective. Please ensure your baby stays well-hydrated with frequent breastfeeds, formula, or Oral Rehydration Salts (ORS). Since the diarrhea has lasted four days, it is very important to consult your pediatrician to confirm the correct dosage and ensure there is no dehydration. Seek immediate medical care if you notice high fever, lethargy, or blood in the stool.