Mom's please give advise, FTM here

My LO is 16 months, got RSV from daycare, he started showing symptoms last week Friday, we took him to the doctor on the Monday and he got Antibiotics and some stuff for the nebulizer, it's now Sunday night and hea doing so much better, eating food again no fever runny nose has stopped and has finished hes course of meds. However he still coughing every now and then and it still sounds very chesty when he breathes (not all the time) it doesn't sound like wheezing but he's chest sounds like it's got phlegm in still. I've been carrying on with the nebulizer and cleaning and suctioning out hes nose, I do also pat on hes back hard to break it up. I'm thinking I should take him back to the doctor... thoughts? Whats to long for a baby to have this chesty cough after being ill?