hi there, sore throat
,listlessness and sore neck without any other symptoms sounds to me like just the flu and not indicative of meningitis
but do keep a close watch on him, give him some anti-pyretic with anti-inflammatory combination, plenty of fluids and rest and he shoould recover in 2-3 days. If he does happen to high grade fever, neck stiffness
then you mayshow him to a pediatritian . till then be relaxed and watchful. Take care.