My nephew 1, 5 years old has vomitted once and had diarrhea since yesterday he s eating potatoes and milk free of lactose and gluten what is it?advice?

Hard to say: It could be a reaction to what he was eating or totally unrelated.Potatoes have specific proteins that some have allergic response to as does cow milk. The kid could also have picked up a stomach virus.A repeat food challenge after the symptoms clear could help define the issue. If the boy tolerates milk or potatoes at a later time, the problem is unrelated.