How do I get my 2 1/2 yr old boy to get rid of his phlegm?

My 2 1/2 year old boy has SO SO much phlegm. He coughs it up but swollows it because he does not know how to speat it out. I know there is a medicine that allows him to swollow his phlegm and then helps him make it in his poop because he has taken it before but I can't seem to find out the name of the medication and the doctor that prescribed it for him has moved and the office where the doctor was at can not find the files. I need to find a way to help him get rid of it because it is so so much, I can tell it bothers him when he coughs it up. My e-mail address is Fun mail me. Do you have an answer for me?

Dear anonymous_coward,
First you must take him back to a doctor...even if it means sitting in your local clinic or emergency ward for several hours. Phlegm can be a sign that the little lungs aren't working the best and a few simple tests a doctor can determine what the problem is.
Sue...good luck