Itchy, scratchy throats, accompanied by a fever, headache and chills, could be strep throat. Strep throat is a contagious infection caused by bacteria. Symptoms can appear suddenly, without a cough or other cold symptoms. In fact, a cough and congested nose make it more likely that a person has a viral sore throat, rather than strep. If your child has signs of strep, which may include stomachache, nausea or vomiting, see your pediatrician.