Hi my toddler who is now 2years old has been coughing for the past 8months.the cough comes and goes.at first it started of dry as the months progressed it came again starting off dry and ending up wet.at times the cough is so bad it lasts an hour.at the end of the cough he spews thick white mucus .he has had a tb test bt it came out negative,he s not asthmatic.I have tried alcophlyllex,benilyn mucus realese,adcolintctopen,adco linctus tussi infans,theophen,nothnign seem to work.