Have you visited PD? Will prescribe cough medicine. Just observe n see will recover in few days. Avoid giving snacks/Milo etc Give plenty of water. Give fish n veggies more. Apply ruyi oil on the front n back area before sleep , If you have, in case awake again in e middle night , can repeat again. ( apply a few drops will do )
Pd will advice what meds to take. It will be safer.
Best to consult the pediatrician..