@krishnareddy84 Hello and welcome to our site. That has to be very disconcerting to have your child coughing and sneezing so much and not find answers. Was your home flooded by hurricane Harvie by any chance? Or your son's day care? Oftentimes; microbes are left in the woodwork that cause respitory issues. Maybe consider taking him to an Infectious Disease dr. Can also try restricting his diet for a few weeks, eliminate milk/dairy, eggs, and gluten (bread, flour, cereal, pasta) do one category at a time. It could be that he has a common food alergy. I know he had an allergy test that turned up nothing. I too had a constant cough and was given both kinds of allergy tests. No food allergies turned up on mine; but, I did the elimination diet and found that dairy and gluten was causing my cough. Keep searching for answers, Google all that you can, maybe get second or third opinions.