Hello Welcome to HCM Most common cause of throat infection (upper respiratory) is viral fevers. Viral infections usually have a period of prodrome with body pains, muscle aches, nausea followed by sore throat and fever which last for about 1week later follwed by a period of convalesence where person feels tired, light headed nad occasional dizzy with loss of appetite. This period can last for about a week to two weeks. Your friend could be in convalescent period, he requires adequate bed rest, healthy diet. But if symptoms are severe and persist for prolonged period consult your physician as early as possible. I hope u find this info helpful. Wish ur friend a speedy recovery.