child with productive bad cough

My son has a bad cough that is productive, but it sounds like he has a hard time coughing things up when he gets sick.  It is worse when he lays down during naptime and at night. His teacher at school says it sounds barkier than the other kids. I treat it with robitussin dm and that helps a lot.  We recently went to the pediatrician and I described the cough to him as his main symptom when he has a cold, but it is associated with a runny and congested nose.  The pediatrician suggested maybe he had asthma and we could put him on long term inhaled steroids for this.  Well, both my husband and I are physicians, and we did not really want to go the steroid route.  My question is, could this just be a normal part of the colds that he gets and his cough is just usually a bad part of it.  He is 3 years old.  Also, would something like albuterol help if he were bronchocontricting and that were causing coughing, but no wheezing?  Also, does the asthma cough sound productive?  Thanks for your help.