4 yr old has a cough day & night. Night cough for 2 wks. Added day cough 1wk. Dry cough. When worry? No fever. Vomiting 1 day prior to day cough.

Time for a visit. Most viral infections (colds) should improve after a week. Since your child's symptoms have lasted longer than that and are expanding I would consider a medical office visit. Cough at night may be reactive airway disease and might benefit from inhaled albuterol. There is a mild respiratory infection - Mycoplasma - that can cause mild cough for weeks especially at night.