What do i give my 7 & 1/2 month old baby with bad chest congestion and dry cough?

about 2 and 1/2 weeks ago my baby woke up with a bad cough and chest congestion out of no where he was coughing every 5 minutes non stop. took him to the urgent clinic since it was sunday and his dr was closed. they gave me albuterol to help with the cough/breathing (makes a wheezing sound every so often) and zithromax (said it was bronchitis) the next day took him to his dr and told me not to give him those med and they said he had ear infection and the congestion would clear up. also had x rays done to check for pneumonia ( thank God everything was fine) well 1 waited a week and he was still coughing w/chest congestion so i took him again this week. this time they gave me a steriod because he belives it could be croup. well it has been been 6 days and he still has bad chest congestion i can hear it everytime he breathes i have tried vapor rubs, humidifiers, but nothing i am going to make another appt. the chest congestion is what really worries me any suggestions thanks