Suggest Treatment For Cough And Nausea After Exposure To Measles

Hi my son had an URI and was in the ED here in CA on 1/17 to treat his asthma. At which point he was exposed to measles I have been informed. He still has a strong cough, is now nauseated, very tired, but no fevers. No maculopapular rash at this point either. We are 12 days out from exposure and I know incubation period can be up to 21 days. He also is falling asleep in school and just not himself. Should I be concerned? Oh and he is up to date on vaccinations.