2yr10 month old- has had fever for 2.5 days- runny nose-and conjuctivitis- being treated- now cough-- visited CHKD this am- how long will fever last?

Unknown . Usually febrile illnesses in children last days to weeks depending one jay the diagnosis is. The fever lasts typically in terms of a few days. The best thing to do would be to call your pediatrician back and ask them. They have all the info needed to give your the best answer, however nobody can predict the future. Hope this helps!
Mgt/workup. If the fever lasts five days or more, I would advise another visit to rule out Kawasaki's Disease. Check for any rash, swelling or peeling of the skin. Typically while on antibiotics for a bacterial illness, the fever should be gone in two days. Other possible causes include Adenovirus. If the illness is prolonged, anothe PCP appointment is indicated.