Is this about your child as you have not mentioned this!
It is likely he is having bronchospasm
(wheeze that you can hear, and asthma if it continues) and manifests as cough in little children.
Gastroesophageal reflux disease
is another possibility although unlikely in this setting.
I would suggest levolin
) syrup (1mg/5ml) 5ml once to twice daily with calpol if he has fever.
Viral induced wheeze is the most likely explanation which is why he is not responding.
Let your GP see him again or take him to A&E.