My son wbo is going ti be 6 years in april is all the time having very bad cough although we tired almost all.mesications even nubilze him regularly?

See specialist: Chronic cough is a common problem and typically a lung specialist (allergist or pulmonologist) can determine the cause and find effective treatment. If the usual causes have been addressed such as asthma, post nasal drip from allergies or sinus infections and stomach acid reflux, then a more thorough evaluation is in order.

Cough: A young person with a cough that is chronic and no fever usually can be asthma. Many people think that wheezing is the only thing to think of but cough can be just as important. The other common cause is acid reflux that spills in his lungs and causes the cough. Other causes can be whooping cough, tumors in the lung, etc. I would continue to look for the causes. Some times a foreign body aspirated.