Kiwi and blueberries sounds okay! You might want to cut down his milk as they clause phlegm. Everytime my baby coughing badly, I’ll cut his milk intake to half
My girl just recovered from cough. I brought her to see the doctor and doctor told me to skip all fruits. If you really want to give, make sure it is not cold.
I'm not sure, but it will be better if you ask advise from a pediatrician.