I don't know which doctors you have seen but you need to see a paediatrician preferably in a teaching hospital paediatric respiratory clinic. If you are in Lagos, you can bring the child with a referral letter to LUTH paediatric respiratory clinic on Fridays 8AM.
Any child coughing for more than 2 weeks should be seen by a paediatrician for further evaluation and management.
There are many causes of persistent or prolonged cough for example bronchial asthma or tuberculosis e.t.c
There are many causes of persistent or prolonged cough for example bronchial asthma or tuberculosis e.t.c