Horrible cough

[~clover~]

DS has been on & off sick for about 4 weeks. He did have an infection, but it cleared up about 2 weeks ago, before I got to a doctor.
He's not so great again today though. No fevers or green or yellow snot, but he has a very wet cough & is having trouble sleeping.

What can I do/give to stop the coughing so he can sleep? He just had about a half hour nap & coughed to the point of gagging almost the whole time. Now he's awake he isn't choking & can breath between, but its still constant coughing.

I don't have cough medicines in the cupboard, have never had them, or used them, coz I know they shouldn't really be given. What else can I do?