Constant Cough and Cold. Of this soon.

My 19 months old son Vedant has been suffering from constant cough and cold from past 2 months, even though we have been giving him ayurvedic cough syrup, Balbhadra syrup and oxy syrup along-with home remedies such as kadha (made of Tulasi, black pepper, ginger), jaiphal with honey, garlic mustard oil massage etc. Most common symptoms include coughing with  sometimes sneezing and running nose .Occasionally, congestion seems more high with blocked nose, open mouth, noisy breething. It all started first on June 14th with sneezing, watery eyes and running nose which was followed by high fever (about 103 degrees) for 2 days. Post medications fever was gone but cough have been almost persistent since then. In this period of twice or thrice in between we felt some improvements but cold and cough reappeared every time. Kindly suggest the remedy/treatment for him to get rid of this soon.