It is very common for children to catch colds, and this is likely a coincidence rather than a direct result of eating oranges, though cool foods can sometimes temporarily irritate the throat. To help him feel better, keep your son well-hydrated with warm fluids like warm water or clear broths. If he is over one year old, a teaspoon of honey can naturally soothe his cough. Please avoid giving over-the-counter cough or cold medications without consulting a pediatrician first, as safety and dosage depend heavily on his exact age and weight. If he has a fever or discomfort, a doctor can advise the correct dose of generic paracetamol.