L.K.
Has he had roseola yet? My 20 month old had the same symptoms (fever and lack of other symptoms) a few months ago and the doc said it was likely roseola and a bumpy rash would appear when the fever broke, or shortly thereafter. Sure enough, after two days of fevers over 104 and two days of no other symptoms, she got the rash and it lasted about a day and a half. It's really contagious, but pretty harmless. It sounds like you're doing a great job keeping the fever down and keeping him hydrated!