marshall's disease??

My 6yr old son (a twin) has suffered from a fever virus once a month for a week for at least 10 months (documented). He has no other symptoms besides a fever ranging from 101 -102.7 for nearly 5 days. we did all the blood tests and nothing has come up. The pediatrician says to take out the tonsils but, the ENT says not to. THe ped also said it might be marshall's disease, in which case he could out grow this fever virus eventually. His twin had his tonsils taken out but that was b/c of sleep apnea (no similarities, right?)
i even took him to a homeopath who prescribed lycene and an anti viral drop. no change. i would like to know if you would recommend taking out the tonsils and adnoids anyway and besides steroids, is there another approach for treatment? i should mention that my son is very tired in the afternoons and is having a lot of trouble learning and retaining information like letters and their sounds and words that begin w each letter. is this all related?
(born @36wks, 4.6lbs, weight 41lbs)