Hello lisadenton,
A child having cough for more then 6 months MUST be evaluated. I would advice you to take him to a paediatrician for a proper work up. As his cough is more in night time, he may have bronchoconstriction, which needs to be evaluated. In the mean time you can give him warm water to drink, you can try honey at night time. Also making him sleep in semi reclined position may help.
Hope your child gets well soon.

Hello Lisa,

Thanks for posting on HCM,

From your description, your son is having a chronic pneumopathy or chronic bronchitis and when chest infection becomes chronic there is a need to start investigating on the causative germs. There could be resistance or germs that cause atypical pneumonia like legionella, mycoplasma, chlamydophila and even TB, pneumocystic carinii etc. If the infection was typical germs and antibiotics were given adequately, then it is very possible that there could have been resistance to the antibiotics used and this will require that another class of antibiotics that can cover typical germs be given. A sputum analysis + culture (to find acid fast bacilli to determine if TB and also other germs) will be needed and others such as Complete blood count (CBC), Blood cultures, Blood tests to identify the bacteria, Bronchoscopy (rarely needed), CT scan of the chest, Open lung biopsy (only done in very serious illnesses when the diagnosis cannot be made from other sources).
Determining the cause of the infection is the first major step. Ones specific germ isolated proper course of antibiotics will be indicated and your son will finally get some relief. Also needed to his treatment will be mucolytic, maybe some steroids to reduce lung inflammation (and also chest pain if present), he will require much fluids etc. Antibiotics used for atypical germs include azithromycin, erythromycin, floroquinolones, tetracyclines etc. If TB then specific antiTB regimens will be provided by the treating doctors.
Other causes of lung affection need to be excluded ( a wide range exist, your son's doctor should be able to lead you to the right direction and maybe direct you to a pulmologist).

Hope this helps