 [ Symptoms ] possible cause of a severe headache with radiating lower back pain son came home from working out after school on thursday and started running a fever on friday fever has subsided but still has a headache and lower back discomfort that runs down through his rear and into his legs [ Disease ] have you checked if has had a fall somewhere or hurt while playing please do not ignore and take him to a doctor hope he gets well soon as a mother do understand how traumatising it can be when kids fall ill take care