PLEASE HELP ME

I have a pitbull who is about 8 months old and he is sneezing and coughing quite a bit he has done this for as long as i can remember, we got him at about 8 weeks , he has all his shots and up to date on heart worm medication i do tend to be a little worry wart i mean he binks funny i wanna bring him to the dr so i just dont know what to do PLEASE HELP ME?
   
we brought him to the vet and they said nothing seems wrong but he never coughs when we are there they have give him some meds that worked for a minute but it comes back but mind you he eats and drinks and goes to the bathroom fine and he has TONS of energy i mean nothing is abnormal about him at all except the cough and sneeze

See my other response to your inquiry.