D.M.
My son's Pediatrician told me that 3 days of being sick wiht or without a fever means call the doctor...so, if it's been that long please take your son to see his Pedi right away.
Also, the cool air humidifiers are more widely used during colds...I don't know why eithery. Saline drops and bulb syringe for nose. Baby vapo rub. Pedicare gentel vapors nightlight plug-in.
These are all great ways to keep your kiddo comfy. Just make sure if it lasts longer than 3 days you give the Pedi a call.