Suggest Remedy For Chronic Headache And Sore Throat Post Treatment For Mononucleosis

my son is 11 years old and has been diagnosed with mono. he has missed 1 1/2 months of school . last week he started back for 1/2 days and yesterday a full day because he had a really good weekend. only having a slight headache throughout the day. then last night the headache seemed to get worse as the evening went on. today he wasnt able to go to school due to the neck pain. and he continues to have occasional severe headaches, aches and pains and a sore throat. is there anything we can do to improve his health and make him feel better so he doesnt miss anymore school