Bulldogs World

Hi everyone, I am a new member and am asking for some advice.  My 10 month old pup contracted kennel cough and although the antibiotics seemed to clear up most of the kennel cough symptoms he has never really got rid of this chesty cough.  He has been in and out of the vets ever since, antibiotics does seem to help, but doesnt clear it up totally.  He coughs to the point of gagging after\during eating and drinking which often leads him to throwing up he will also cough throughout the evening\ when sleeping.  He is energetic, playful, has a good appetite , but just cant seem to shake the "cough".  A recent Xray at the vets showed that he has fluid in his lungs, and his narrow windpipe is making it hard for him to clear this mucus\fluid. We live in a small city in New Zealand and our Vet doesnt have much prior experience with Bulldogs.  Any suggestions on what we can do to relieve his symptoms?