He is mostly having gastroenteritis, or commonly called as food poisoning. Did u start feeding him anything new ? Or if you are still breast feeding, did u have any new food item? Does he have any other issues like fever or rash??
Next Steps
There is no medications to stop loose stools. Don't worry, both vomiting and loose stools lose water from our body, so keep giving him small amounts of milk or fluids. Vomiting can be controlled, but please ask for offline or online consultation for prescription.